What is considered a dangerous fever. How to differentiate between high and low grade fevers. When should you be concerned about a child’s fever. What are effective methods to reduce fever in children and adults.

Understanding Fever: What It Is and Why It Occurs

Fever is a common bodily response that often causes concern, especially in parents. But what exactly is a fever, and why does it occur? A fever is defined as a body temperature that rises above the normal range of 98.6°F (37°C). It’s important to note that body temperature can fluctuate throughout the day, so a slight elevation doesn’t always indicate a fever.

Why does the body develop a fever? Contrary to popular belief, fever isn’t an illness itself. Instead, it’s a sign that the body’s immune system is actively fighting against invaders, typically an infection or illness. When the body detects pathogens, it raises its internal temperature to create an environment less hospitable for these harmful organisms.

Common Symptoms Accompanying Fever

• Chills and sweating
• Muscle aches
• Changes in appetite
• Dehydration
• Weakness
• Behavioral changes

Is fever always a cause for concern? Not necessarily. In many cases, a low-grade fever is a sign that the body’s defense mechanisms are working effectively. However, understanding when a fever becomes dangerous is crucial for proper care and timely medical intervention.

Classifying Fevers: Low-Grade vs High-Grade

Fevers are typically categorized into two main types: low-grade and high-grade. Understanding the difference between these can help in assessing the severity of the condition and determining the appropriate course of action.

Low-Grade Fever

A low-grade fever is generally defined as a body temperature between 100.4°F (38°C) and 102.2°F (39°C). While it may cause discomfort, a low-grade fever is often not a cause for immediate concern in older children and adults. It’s the body’s way of fighting off infections and can often be managed at home with proper care and monitoring.

High-Grade Fever

A high-grade fever is characterized by a body temperature above 102.2°F (39°C). This level of fever often indicates a more severe infection or illness and may require medical attention, especially in young children, elderly individuals, or those with compromised immune systems.

Can the severity of an illness be determined solely by the temperature? It’s important to note that the number on the thermometer isn’t always the best indicator of how sick a person is. Other factors, such as age, behavior, duration of the fever, and accompanying symptoms, should also be taken into account when assessing the severity of a condition.

Age-Specific Fever Guidelines: When to Seek Medical Attention

The approach to managing fever varies significantly depending on the age of the individual. What may be considered a mild fever in an adult could be potentially dangerous for an infant. Let’s break down the guidelines for different age groups:

Newborns and Infants (0-3 months)

For the youngest and most vulnerable age group, any fever is considered serious. If your infant has a rectal temperature of 100.4°F (38°C) or higher, it’s crucial to seek immediate medical attention. Similarly, a temperature lower than 97.7°F (36.5°C) when taken rectally also warrants a call to the doctor.

Babies and Toddlers (3 months to 3 years)

For this age group, a fever of 102.2°F (39°C) or higher is a reason to contact your pediatrician. Pay close attention to how your child responds to over-the-counter fever reducers. If the fever doesn’t respond to medication, it could indicate a more serious condition.

Older Children (3 years and above)

For children over 3 years old, a fever over 102°F (38.9°C) that persists for more than two days may be a cause for concern. If the fever lasts for five or more days, regardless of its height, it’s advisable to consult with a healthcare provider.

Are there other symptoms that should prompt immediate medical attention regardless of age? Yes, certain symptoms in combination with fever require urgent care. These include:

• Difficulty breathing or swallowing
• Persistent vomiting or inability to keep fluids down
• Signs of dehydration (decreased urination, dry mouth)
• Unexplained rash, especially if dark in color
• Stiff neck or severe headache
• Extreme lethargy or difficulty waking

Febrile Seizures: A Rare but Concerning Complication

While discussing fever in children, it’s important to address a rare but potentially alarming complication known as febrile seizures. These are convulsions that can occur in some children, usually between the ages of 6 months and 5 years, when they have a fever.

Understanding Febrile Seizures

Febrile seizures may involve jerking motions or appear as if the child is passing out. While they can be frightening to witness, most febrile seizures are short-lived and don’t cause long-term health problems. However, they should always be taken seriously.

How should you respond if your child experiences a febrile seizure? If your child has a seizure, it’s important to:

1. Place them on a safe, flat surface
2. Turn them onto their side to prevent choking
3. Do not try to restrain them or put anything in their mouth
4. Time the duration of the seizure
5. Call your doctor immediately or seek emergency care if the seizure lasts longer than 5 minutes

While febrile seizures can be alarming, it’s crucial to remember that they’re generally not harmful to the child’s long-term health. However, they should always be reported to your healthcare provider for proper evaluation and guidance.

Accurate Temperature Measurement: Choosing the Right Method

Accurate temperature measurement is crucial for properly assessing and managing fever. The method of temperature taking can vary based on the age of the individual and the type of thermometer available.

Temperature Taking Methods by Age Group

For newborns and infants up to 3 months:

• Rectal temperature using a digital thermometer is considered the most accurate method
• Some research suggests that temporal artery thermometers can also be accurate for this age group, but consult your pediatrician for guidance

For babies and toddlers (3 months to 3 years):

• Rectal temperature remains the most accurate method
• Digital thermometers used in the underarm or temporal artery scanners can also be effective
• In-ear thermometers can be used for babies 6 months and older

For children 4 years and older:

• Oral temperature using a digital thermometer under the tongue is effective
• Ear thermometers, temporal artery scanners, or underarm measurements are also suitable

Is there a waiting period required before taking temperature after eating or drinking? For oral temperature measurements, it’s advisable to wait at least 30 minutes after the child has eaten or had anything to drink to ensure accuracy.

Fever Reduction Techniques: Home Remedies and Medications

While fever is often a sign that the body is fighting infection, there are times when fever reduction is necessary for comfort or to prevent complications. Here are some effective techniques for reducing fever:

Home Remedies for Fever Reduction

1. Keep the person hydrated with plenty of fluids
2. Dress in lightweight, breathable clothing
3. Keep the room temperature comfortable, not too hot or cold
4. Use a lukewarm compress on the forehead, wrists, or back of the neck
5. Encourage rest and avoid overexertion

Over-the-Counter Medications

For fever reduction, the following medications are commonly used:

• Acetaminophen (Tylenol)
• Ibuprofen (Advil, Motrin)

Is it safe to give over-the-counter fever reducers to infants? Always consult with your pediatrician before administering any medication to infants under 1 year of age. They can provide guidance on appropriate dosages based on your child’s age and weight.

It’s important to note that aspirin should not be given to children or teenagers due to the risk of Reye’s syndrome, a rare but serious condition that can affect the brain and liver.

When to Trust Your Instincts: Seeking Medical Advice

While guidelines and temperature readings are helpful, it’s crucial to remember that you know your child or your own body best. Sometimes, intuition plays a significant role in determining when medical attention is necessary.

Trusting Parental Instinct

If you feel that something is seriously wrong, despite temperature readings that may not seem alarming, it’s always better to err on the side of caution. Pediatricians and healthcare providers would rather address your concerns than have you delay seeking care for a potentially serious condition.

Signs That Warrant Immediate Medical Attention

Regardless of the temperature reading, seek immediate medical care if you or your child experiences:

• Severe, persistent headache
• Confusion or altered mental state
• Persistent vomiting
• Difficulty breathing
• Severe abdominal pain
• Unusual skin rash, especially if it’s rapidly spreading

Should you feel hesitant about contacting your healthcare provider with concerns? Absolutely not. Healthcare providers are there to help and would much rather address your concerns early than deal with complications that arise from delayed care. When it comes to fever and overall health, it’s always better to be safe than sorry.

When Is a Fever Too High for a Child, Toddler, or Newborn?

Your little one feels warm to the touch. After taking their temperature, you realize it’s 103°F — a fever!

Even if this scenario sounds super familiar, it can still catch you off guard. Before you race to the doctor, though, take a deep breath.

It’s helpful to familiarize yourself with fever, its function in the human body, and any warning signs that may mean it’s serious — or, alternatively, when you can relax.

Related: What you should do if your newborn has a cold

Normal body temperature is around 98.6°F, though it may fluctuate slightly higher or lower throughout the day. A fever starts with any temperature that reaches 100.4°F or above.

A temperature between 100.4°F and 102.2°F is considered a low-grade fever; a temperature above 102.2°F is considered a high fever.

A fever isn’t a sickness in itself. Instead, elevated body temperature is a sign that your child’s immune system is hard at work fighting off some type of invader — usually an illness or infection.

Along with an elevated temperature, your child may experience these fever symptoms:

• chills
• sweating
• muscle aches
• appetite changes
• dehydration
• weakness
• changes in behavior

The number on the thermometer isn’t always the best indicator of how sick your child is. You need to take into account:

• your child’s age
• how they’re acting
• the number of days they’ve had the fever
• any other symptoms you observe

For example, a small percentage of younger kids — usually between the ages of 6 months and 5 years, according to Mayo Clinic — may even experience febrile seizures. These seizures may involve jerking motions or look like your child is passing out.

Call your doctor if your child experiences a seizure or call 911 if the seizure lasts longer than 5 minutes.

In young babies, even slight temperatures may be a reason for concern. That’s why you should always contact your doctor or head to urgent care if your little one has any fever that’s 100. 4°F or above. (The same goes with a temperature lower than 97.7°F when taken rectally.)

You should also head to the ER if your baby has a fever and any of the following symptoms:

• trouble feeding
• trouble breathing
• unexplained rash
• vomiting or diarrhea
• acting differently (lethargic, inconsolable, etc.)

For the most accurate read, take your infant’s temperature with a digital thermometer inserted rectally (yes, that’s the best way). There’s some research to suggest that temporal artery thermometers can work accurately for this age as well, but speak with your doctor for guidelines.

Related: Baby fever 101: How to care for your child

In older babies and toddlers, call your doctor if your child’s fever is 102.2°F or above.

You’ll also want to pay attention to how your child responds to over-the-counter (OTC) medications. Always ask your pediatrician about giving any OTC drugs to babies under age 1.

If the fever doesn’t respond to fever reducers (ibuprofen, acetaminophen), there may be something more serious going on.

Other symptoms that warrant urgent care:

• trouble waking up
• trouble breathing
• decreased urine output
• difficulty keeping fluids down (vomiting)
• unexplained dark rash
• stiff neck, abdominal pain, or other concerns

Rectal reading may still be the best way to get an accurate temperature with older babies and toddlers. That said, you may also have success using a digital thermometer in the underarm or a temporal artery scanner.

If you have an in-ear thermometer, you’ll want to wait until your child is at least 6 months old to use it.

Related: Symptoms of fever in adults, children, and babies

For kids over age 3, a fever over 102° F that lasts for 2 or more days may be a reason for concern.

If their doctor tells you to keep an eye on it, a couple days may be OK.

However, if your little one has had a fever for 5 or more days, be sure to call back to make an appointment with their doctor. The same goes for a fever that doesn’t lower with OTC medications.

Other symptoms that may warrant urgent care:

• trouble breathing or swallowing
• difficulty keeping fluids down (vomiting)
• burning with urination or infrequent urination
• unexplained dark rash
• stiff neck, abdominal pain, or other concerns
• acting lethargic or difficult to wake

For children ages 4 and up, you may use a digital thermometer to take temperature orally under the tongue (if your child can hold it there long enough). For best results, be sure to wait 30 minutes after your child last ate or drank anything.

You may also take a reading in the ear or armpit — or even on the forehead using a temporal artery thermometer.

You know your child best. If you feel in your gut something is wrong, don’t hesitate to give your pediatrician’s office a call. And don’t feel silly — they get questions all the time and would rather you be extra safe when it comes to your child’s health.

Get in touch with your doctor or urgent care if:

• Your baby is younger than 3 months old with a fever over 100. 4°F.
• Your baby (ages 3 to 6 months) has a temperature of 102°F and is acting unlike themselves (lethargic, uncomfortable, etc.).
• Your older baby (ages 6 to 24 months) has a temperature over 102°F that lasts more than 1 day with no other signs of illness, like cough or diarrhea.
• Your child’s fever has been present for 5 days or longer.
• Your little one’s fever is 104°F or above, regardless of the presence of other symptoms.
• Your child’s fever doesn’t lower even when taking fever reducers.
• Your child is inconsolable, lethargic, or not acting like themselves.
• Your little one is showing signs of dehydration, like decreased urine output. (FYI: Babies should wet at least 4 diapers per day; older kids should urinate at least once every 8 to 12 hours.)
• Your child has recently had immunizations and has a fever of 102° F or higher.
• Your child has recently had immunizations and has had an elevated temperature for more than 48 hours.
• Your child has a febrile seizure. Call your doctor if it lasts less than 5 minutes. If longer, call 911.

Remember: You should always call your doctor for fever in babies under 3 months old.

Older kids do get fevers, though. So while it’s important to know when you should head to the doctor, it’s equally key to know when you can relax and monitor on your own.

In many cases, a fever is their body’s response to fighting off a mild illness. It will resolve on its own when the illness winds down and your child gets better.

You may be able to monitor at home if:

• A fever lasts fewer than 3 to 5 days, provided your little one is acting like themselves. Observe their eating, drinking, and play patterns to see if they’re at their normal level of activity. Being slightly more tired than usual is expected, though.
• The fever is below 102.5°F in children ages 3 months to 3 years or below 103°F in older kids. (Of course, this is provided there are no other warning signs. ) Temperatures in this range are common and don’t necessarily signal an emergency.
• Your child gets a low-grade fever following immunizations. A slight temperature in the first couple of days after shots isn’t necessarily a reason for concern.

Related: What are the flu symptoms in kids and how is it treated?

Chances are, your little one will have many fevers in their lifetime.

Pay attention to the number on the thermometer but also look at your child. If they’re acting normally and drinking enough fluids — and their fever goes away relatively quickly — you can relax and try at-home comfort measures, like giving them a lukewarm bath.

Otherwise, get in touch with your doctor or head to urgent care to get things checked out.

What Is Considered a Fever? Symptoms & Treatment

It’s relatively common knowledge that the normal body temperature is 98.6° F (37° C), but your core body temperature actually varies by a degree or so throughout the day. For instance, your body temperature will be slightly lower in the morning and higher in the late afternoon into the evening. However, certain factors may cause your body temperature to dive below what’s considered normal or spike to pyrexia, more commonly known as a fever.

Unlike hypothermia, an emergency condition that develops when your body temperature reaches 95° F (35° C) or lower, a fever is fairly common and, in most cases, not very dangerous. Developing an elevated body temperature—whether it’s a high or low grade fever—is usually your body’s response to infection. Luckily, fevers typically last only a few days and there are several treatment options that can help you feel more comfortable.

What Is a Fever?

The normal human body temperature is 98.6° F (37° C), but other factors, including illness, certain medications, and specific medical conditions, can cause your temperature to rise. A fever is your body’s natural response to fighting an infection.

Any temperature between 98. 6-100.4° F (37-38° C) is considered a low-grade fever, while any temperature above 103° F (39.4° C) is considered a high-grade fever. Unlike a significantly lower-than-normal body temperature, having a higher temperature isn’t necessarily dangerous.

One factor that differentiates what is considered a low or high body temperature is age. For adults and children, 95.1-96.9° F (35-36° C) is low and 100.4-103° F (38-39.4° C) is high, but neither case is necessarily an emergency. However, if a baby less than three months old experiences a temperature in either range, it may indicate a serious infection that requires immediate medical care.

This easy-to-read chart shows what various body temperatures mean and when to seek care. The measurements in this chart were made by mouth with the thermometer under the tongue.

See a doctor online.

Start my visit

Fever in Children

When adults develop a fever, they usually feel uncomfortable, but there’s typically no cause for concern, although an exception to this rule arises when an adult is undergoing chemotherapy treatment or has any condition which impairs the body’s ability to fight infections. When infants, toddlers, and children develop fever symptoms, they are more likely to need medical care.

If your toddler or child has a fever, but is still responsive, eating, drinking fluids, and playing, there’s no cause for concern. However, if your infant, toddler, or child experiences the following, you should either call your doctor or seek immediate care:

• More Irritable than usual
• Vomiting repeatedly
• A fever lasting more than three days
• Appears listless and unresponsive

Complications in children

Although fevers in children are quite common, some children between the ages of six months and five years may experience complications, such as febrile seizures or convulsions. Luckily, most children who experience fever-induced convulsions suffer no lasting effects and are not thought to be at higher risk of developing seizures or epilepsy later in life.

If your child has a seizure resulting from a fever, do the following:

• Lay your child on the floor on his or her side or stomach
• Clear the vicinity of any sharp objects
• Loosen any tight clothing
• Do not try to stop the seizure yourself
• Hold your child in place to prevent injury

Fever symptoms generally cause discomfort because your body is working to fight off an infection.

When you develop pyrexia, the most common symptoms you might experience include sweats, shivers, and headaches. Other common fever symptoms include:

• Chills
• Muscle aches
• Loss of appetite
• Irritability
• Dehydration
• Lethargy

What Causes a Fever?

Your body’s internal thermostat is controlled by a small area in your brain called the hypothalamus. When your hypothalamus sets your internal body temperature higher than usual, this results in a fever. Usually the hypothalamus will reset this internal thermostat to normal within a few days. Although infection (which can be caused by either bacteria or viruses) is more often than not the cause of your fever, other causes include:

• Heat exhaustion
• Inflammatory conditions, such as rheumatoid arthritis
• Malignant tumors
• Drugs for high blood pressure and/or seizures
• Specific immunizations, such as diphtheria, tetanus, and pneumococcal vaccines

Diagnosing a Fever

Unlike many other illnesses, diagnosing a fever is something you can do at home. You should only seek medical attention if your high fever lasts more than a few days or is accompanied by any concerning symptoms.

Taking a temperature

The most obvious indication of a fever is a body temperature that’s higher than normal. The best way to measure your temperature is to take it using a thermometer. There are several different types of thermometers, but the most popular is a digital one, which you can use orally, rectally or axillary (under your armpit). Regardless of which type of thermometer you use, always be sure that the batteries aren’t expired as that may skew the results.

Other types of thermometers include a tympanic thermometer, which measures the temperature inside of the ear by reading the infrared heat. Most pediatricians use this method to take babies’ temperature if they’re three months or older.

Here’s how to use a digital thermometer:

• Make sure your hands and the thermometer are clean.
• Do not eat or drink anything for at least five minutes before you take your temperature because the food/drink may skew the results.
• Place the thermometer tip under the tongue, into the anus (using a petroleum jelly), or into your armpit and wait about 40 seconds. Most thermometers will beep when they have an accurate reading.
• Remove the thermometer and clean it with soap and water or with alcohol. Afterwards, be sure to rinse it.

Treatments for Fever

If you have a low-grade fever (up to 100.4° F and 38° C ), the best treatment may be letting the fever run its course. Having a slightly elevated body temperature can help get rid of the illness-causing microbes that are responsible for your cold, flu, or other viral infection. In cases of a high fever, there are a number of actions you can take to help lower your body temperature.

How to break a fever

As previously mentioned, having a fever isn’t necessarily a bad thing. It’s a sign that your body is fighting off an infection. However, in some cases, breaking your fever, or reducing your body’s temperature, can be helpful in making you feel more comfortable. Some of the most common ways to break a fever include:

• Over-the-counter medications: There are a variety of over-the-counter medications, such as acetaminophen and ibuprofen, that can help break your fever. However, taking too much of these medications or using them regularly over a prolonged period of time can cause liver and kidney damage. Children should never take aspirin, as it can cause a potentially fatal disorder called Reye’s syndrome.
• Antibiotics or antivirals: Depending on what’s causing your fever, your doctor may prescribe an antibiotic for a bacterial infection and an antiviral for a viral infection. Taking either, as directed by your doctor, can help break your fever.
• Hydrate: Drink plenty of non-alcoholic or caffeinated fluids to counteract the dehydration associated with fever.
• Let your body rest: Getting ample rest and staying cool can also help lower your fever.

What to eat when you have a fever

While your body and immune system need nutrients to fight off infection, your illness may be accompanied by nausea or lack of appetite. In that case, do not force yourself to eat. In fact, you should only eat if you are able to keep down food and if you feel hungry. Although the best thing you can do for a fever is to drink plenty of fluids, eating chicken soup has proven helpful as well. Other helpful foods include:

• Greek yogurt: If you can tolerate dairy, greek yogurt is an excellent food to eat when you have a fever because it contains a lot of probiotics, which help your immune system.
• Coconut water: Coconut water is naturally rich in electrolytes and potassium.
• Fruits with vitamin C: Most fruits are at least 80% water, making them an excellent source of hydration. Fruits containing vitamin C, such as oranges, can also help improve your immune response.
• Protein-rich foods: Foods including beans, nuts, lean meat, and poultry are high in protein, which your immune system needs in order to produce antibodies and fight off an infection.

Fever Prevention

The most effective way to prevent a fever is to avoid contracting an infection. While that’s not always possible, you can take the following steps to minimize your exposure to germs and diseases:

• Wash your hands: Wash your hands often with an antibacterial soap for at least 20 seconds.
• Use hand sanitizer: If you’re traveling and water and soap aren’t immediately available to you, using a hand sanitizer with at least 60% alcohol will help kill any germs.
• Avoid touching your face: Even if you wash your hands or use hand sanitizer, you may still be at risk, so avoid touching your nose, eyes, and mouth to prevent contracting an infection.

When to See a Doctor

Just because you have a fever doesn’t mean you need to pay a visit to the doctor. However, if you have a fever of 103° F (39.4° C), you should call your doctor, especially if your fever is accompanied by any of the following:

• Severe headache
• Skin rash that worsens quickly
• Sensitivity to light
• Stiff neck and/or pain when you bend your head forward
• Mental confusion
• Consistent vomiting
• Difficult breathing and/or chest pain
• Abdominal pain and/or pain when urinating
• Convulsions and seizures
• Severe sore throat or difficulty swallowing
• You are undergoing chemotherapy or other treatments for cancer or have any underlying chronic condition which suppresses your immune system

See a doctor online.

Start my visit

How K Health Can Help

While most fevers you can handle at home, sometimes you may need to speak to a doctor to make sure nothing more serious is going on.

Did you know you can get affordable primary care with the K Health app?

Download K Health to check your symptoms, explore conditions and treatments, and if needed text with a clinician in minutes. K Health’s AI-powered app is based on 20 years of clinical data.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Fever | Didkovsky N.A., Tanasova A.N.

L fever – an increase in body temperature as a result of a non-specific protective and adaptive reaction of the body, characterized by a restructuring of thermoregulation processes and occurring in response to exposure to pathogenic stimuli. There are fever infectious and inflammatory nature (viruses, bacteria, intracellular parasites) and non-infectious genesis (autoimmune processes, allergic diseases, tumors, metabolic disorders, the use of certain drugs, etc.) [2]. The regulation of body temperature is carried out with a complex interaction of the nervous, endocrine and immune systems. The most common trigger in the development of hyperthermia are exogenous pyrogens (bacteria, viruses, toxins, etc.), which, when ingested, stimulate the production of endogenous pyrogens by blood cells [4].

Fig.1. The mechanism of development of fever under the influence of exogenous and endogenous pyrogens. ACTH – ACTH, CRF – corticotropin-releasing factor, PGE2 – prostaglandin E2 (CECIL Textbook of Medicine, 19 h edition).

Currently, 11 cytokines are known to have pyrogenic activity, the most important of which are interleukins – IL-1 and IL-6, as well as tumor necrosis factor – TNF-a [4]. Endogenous pyrogens are produced by stimulated monocytes and macrophages. The properties of pyrogens are also possessed by a-, b- and g-interferons. IL-1 and TNF-a are transported with the blood stream to target cells that carry specific receptors for these cytokines, and act on thermosensitive neurons in the preoptic region of the hypothalamus through increased prostaglandin (PG) synthesis E ₂ and PGF _2a from arachidonic acid.

Fig. 2. Metabolism of arachidonic acid (according to A.A. Yarilin) ​​[3]. International abbreviations for prostaglandins (PG), leukotrienes (LT) and thromboxanes (Tx) are used.

The exact mechanism of “switching” of the thermoregulation center under the action of PG has not yet been established. The direct effect of cytokines on the nervous tissue is not excluded. An increase in body temperature activates metabolic processes, the functions of the nervous, endocrine, and immune systems (an increase in the production of antibodies, interferon, an increase in chemotaxis, phagocytic and bactericidal activity of neutrophils), an increase in the antitoxic function of the liver, and an increase in renal blood flow. IL-1 and TNF-a are able to enhance the immune response by activating T-cells and stimulating the production of IL-2. Under the action of IL-1, B-cell proliferation is enhanced, which is accompanied by an increase in antibody formation. It is important to note that these processes proceed most intensively at a temperature of 39°C. Under the action of endogenous pyrogens, the synthesis of “acute phase” proteins (fibrinogen, C-reactive protein, complement fractions B, C 3-4, alpha-glycoprotein, serum amyloid A, proteinase inhibitors) is stimulated by the liver, which play an important role in specific and non-specific protection. Hyperthermia is accompanied by a decrease in serum levels of iron, zinc and copper, which inhibits the growth and reproduction of microorganisms.

In a typical course, fever goes through the following phases or periods – a prodromal period, a period of temperature rise, a period of relative stability, a period of decrease in body temperature, each of which is accompanied by certain vegetative reactions. What changes accompany the development of fever?

1) Tachycardia. With an increase in body temperature by 1 ° C, an increase in heart rate by 10–15 beats per minute occurs.

2) It is possible to develop extrasystole, which is due to both the direct toxic effect of bacteria and viruses, and the activation of the sympathetic-adrenal system under the influence of cytokines.

3) In the phase of temperature rise, an increase in blood pressure is possible, and in the phase of temperature decrease, blood pressure drops to a collaptoid state against the background of a decrease in TPS.

4) Upon reaching the maximum body temperature, the process of sweating increases significantly (up to 1 liter of sweat per day is possible), which can contribute to a decrease in BCC and lead to a deterioration in the condition of patients with pathologies of the cardiovascular system. Fluid losses are also aggravated by a compensatory increase in respiratory rate at the height of fever.

5) At the height of fever and even after normalization of temperature, transient appearance in the urine of protein, casts and an increase in creatinine levels is possible. These changes are associated with the direct damaging effect of fever.

6) Fever affects the activity of various parts of the gastrointestinal tract, which is manifested by impaired secretion of digestive juices, impaired motility and absorption processes. As a result, there may be a decrease in appetite, the development of a syndrome of impaired absorption and constipation (the latter has a particularly adverse effect on elderly patients). Loss of appetite during fever is associated both with functional disorders of the gastrointestinal tract and with the direct influence of cytokines. So, with prolonged exposure to high concentrations of TNF-a (which has a second name in Western literature – “cachectin”) and partially IL-1, depletion may develop due to the suppression of hunger / appetite (which is most typical for chronic infections and oncological processes).

7) Against the background of fever, metabolic processes in cells increase sharply (with an increase in body temperature by 0.6 ° C, the level of basal metabolism increases by approximately 10%), redox processes accelerate, and oxygen consumption increases. Hyperthermia can increase blood glucose levels, increasing protein catabolism (negative nitrogen balance). Loss of protein up to 300-400 grams per day is possible. A decrease in diuresis against the background of a reduced BCC can lead to the development of metabolic acidosis.

8) Changes in consciousness (from minor to the development of a delirious state) are associated with the release of b-endorphins under the influence of TNF-a and IL-1. The risk group includes young children, the elderly, patients with pathology of the cardiovascular system, as well as people who abuse alcohol.

9) Due to the immaturity of the central nervous system and the imperfection of the thermoregulation system in children under the age of 5 years, the development of febrile convulsions is possible.

10) An increase in body temperature can lead to the activation of latent herpesvirus infection (HSV-1). For reasons that are not completely clear, most often herpetic eruptions accompany diseases caused by a pyogenic bacterial infection (pneumococci, streptococci, meningococci), malaria, and rickettsiosis. Nasolabial herpes is a marker of reduced cellular immunity. It is important to note that subjective sensations during fever are of a different nature. Some patients are sensitive to even small fluctuations in body temperature, while others do not experience discomfort with a significant increase in temperature (for example, with pulmonary tuberculosis). However, in most cases, patients complain of weakness and malaise, headache, pain in the muscles and joints, chilling or excessive sweating, which “pushes” the doctor to prescribe antipyretics. When deciding on the need to prescribe non-steroidal anti-inflammatory drugs (NSAIDs), it is necessary to take into account both positive and potentially dangerous manifestations of fever. It must be remembered that fever, like any protective-adaptive reaction, with the depletion of compensatory mechanisms or with a hyperergic variant, can cause the development of pathological conditions. So, an excessive increase in temperature leads to inhibition of immune responses, impaired function of parenchymal organs, the development of febrile convulsions, functional and degenerative disorders in the cardiovascular and central nervous system. A critical decrease in body temperature can contribute to the development of collapse due to a sharp drop in total peripheral resistance and aggravate the condition of patients with pathology of the cardiovascular system.

So in what case is it necessary to use antipyretics?

An increase in body temperature within 3°C does not have a damaging effect on the human body, however, its increase by more than 6°C (i.e. more than 42.2°C) leads to irreversible changes in brain structures, which is a condition incompatible with life. When deciding on the need to prescribe NSAIDs, it is necessary to take into account the age of the patient, the severity of the underlying and concomitant diseases, as well as the subjective tolerance of fever.

Currently NSAIDs are widely used in the symptomatic treatment of fever in ARVI. However, little attention is paid to non-drug (physical) methods of lowering body temperature, which is especially important in pediatric practice. I would like to remind you that physical methods of lowering the temperature (such as wiping the body with a weak solution of vinegar, applying cold to the area of ​​large arteries, wet wrapping, a warm (not cold!) bath, an enema with water at room temperature) are recommended not only in domestic, but also in modern foreign literature, they can be quite effective and have no side effects. It is necessary to remember such rules for caring for patients with fever, such as an adequate drinking regimen, a sparing diet, mandatory ventilation of the room, and the prohibition to “wrap up” the patient, since the latter prevents heat transfer.

In febrile conditions on the background of infectious and inflammatory diseases, rectal suppositories Cefecon N are used as an antipyretic, anti-inflammatory and analgesic. Cefecon N suppositories are a unique combination of naproxen, caffeine and salicylamide, which ensures high antipyretic, analgesic activity. Cefecon H has a number of advantages over oral NSAIDs.

Before entering the systemic circulation, medicinal substances must pass through the stomach, small intestine, liver, where they are destroyed and adsorbed to a certain (sometimes significant) degree, which can lead to damage to this organ. Even if taken on an empty stomach, drugs enter the systemic circulation on average no earlier than 30 minutes later. When taking drugs orally in the form of powders and especially tablets, there is the greatest likelihood of their local irritating effect on the gastric mucosa.

With the rectal route of administration, the intake of substances adsorbed in the rectum is carried out simultaneously through the circulatory and lymphatic systems, which are especially developed in this area. In this case, an insignificant part of the adsorbed drugs enters the portal vein, which carries blood from the internal organs to the liver. Moreover, bioavailability from the rectal mucosa for a number of drugs is equivalent to that after intravenous administration. Thus, the introduction of NSAIDs in suppositories can reduce the risk of side effects from the gastrointestinal tract and ensure that the full dose of the drug is delivered, regardless of food intake and concomitant therapy (for example, antacids). In this regard, the use of NSAIDs in the form of rectal suppositories (Cefecon N) seems to be a very promising direction.

Despite the fact that, in the understanding of the patient, fever is often an undesirable manifestation of the disease, the doctor, when determining the strategy for treating the patient, must take into account the positive factors of the hyperthermic reaction. Moreover, the elimination of fever should not be the main goal of the therapy (which often occurs in the presence of SARS). It is well known that the course of an infectious disease without a temperature reaction may indicate that the patient has an immunodeficiency state and is an unfavorable prognostic factor.

1. Luchsheva Yu., Cold. How to deal with it. The effectiveness of symptomatic therapy for acute respiratory viral infections // Pharmaceutical Bulletin No. 37 (236), 2001.

2. NSAIDs: the role of rectal suppositories.//Russian Medical Journal, Vol. 10, No. 21(165), 2002, pp. 982–986.

3. Yarilin A.A., Fundamentals of immunology, M. “Medicine”, 1999, pp. 163–168.

4. Bruce Beutler, Steven M. Beutler, The Pathogenesis of Fever// CECIL Textbook of Medicine,19th edition, 1994, p.1568–1571.

5. Cranswick N, Coghlan D., Paracetamol efficacy and safety in children : the first 40 years// Am J Ther, 2000, 7(2): 135–41.

6. Glasow.J.F.T., Middleton B., Reye syndrome – insights on causation and prognosis// Arch Dis Child, 2001, 85, 351–353.

what to do, what temperature is considered high and why it is dangerous, causes and symptoms

Fever, fever – this is what we call an increase in body temperature. This is the most important defense mechanism of the human body and one of the main symptoms of infection. Most often, we encounter a fever with colds and flu. High temperatures cause some discomfort, but it helps to cope with the disease faster. We will tell you why adults have a fever, when it is necessary to bring down the temperature, and in what cases it is not worth it.

Why the temperature rises

¹

Body temperature can rise for various reasons: due to overheating, inflammation, hormonal imbalance. The processes of heat transfer in the human body are regulated by a small part of the brain – the hypothalamus. The temperature rises with any physical or chemical impact on it.

An increase in body temperature associated mainly with infections is called a fever. It develops when biologically active substances, cytokines, act on the hypothalamus. The immune system releases them into the blood in response to the inflammatory process. The production of cytokines is also enhanced by the waste products of microbes.

Fever is one of the main symptoms of an acute respiratory viral infection (ARVI). But it is also a protective reaction of the body, aimed at fighting the virus. When the temperature rises, the immune system synthesizes more leukocytes, which destroy or inactivate pathogenic microbes, and interferons, natural antiviral substances.

What temperature is considered high

^2.3

A temperature above 37˚C measured in the armpit is considered elevated. When measuring temperature in the oral cavity, a temperature of more than 37.2˚C is considered elevated, and in the rectum – more than 37.8˚C.

Types of fever:

● Subfebrile – 37.5–38˚C. Accompanies a chronic or easily flowing acute infection.

● Febrile – 38-39˚C. A frequent companion of most acute inflammatory processes – infectious and non-infectious.

● Pyretic (high) – 39-41˚C. This is one of the signs of a moderate flu. High fever is accompanied by symptoms that worsen well-being.

● Hyperpyretic (critically high) – more than 41˚C. It occurs in a severe form of influenza, causes life-threatening disorders of body functions.

What symptoms accompany fever

^{4, 5}

Subfebrile temperature is accompanied by weakness, feeling of weakness, headache, drowsiness, chills. At a temperature of 38˚C, the skin becomes hot, the cheeks turn red, the patient feels intense heat, dry mouth. Lips dry out and crack. With pyretic fever, nausea and vomiting may join. Hyperpyretic temperature is often accompanied by a disorder of consciousness, delirium.

Fever increases blood pressure and heart rate. An increase in temperature by one degree increases the pulse by 10-15 beats per minute.

What diseases occur with fever

⁶

The most common cause of fever in adults is acute respiratory viral infections (ARVI):

● Coronavirus, rhinovirus infection. This is SARS, affecting mainly the mucous membranes of the nasal cavity and pharynx. Symptoms: runny nose, redness and sore throat, sneezing, coughing. The temperature is subfebrile (37–38˚С) or febrile (38–39C).

● Influenza. Influenza viruses can immediately affect the lower respiratory tract and cause a deep chest cough. Infection is most often accompanied by severe intoxication, which is manifested by headache, aching throughout the body, and severe weakness. The temperature can reach pyretic (39-41˚C) and hyperpyretic (over 41˚C).

● Respiratory syncytial virus infection. It often affects the trachea and bronchi, in a quarter of the patients it leads to pneumonia. Symptoms are similar to the flu, with the difference that intoxication is less pronounced, signs of inflammation of the lower respiratory tract come to the fore – a deep cough with pain behind the sternum.

● Parainfluenza. The virus infects the nasal cavity, pharynx, larynx. The infection is accompanied by a runny nose, bouts of painful coughing, hoarseness, and sometimes a short-term loss of voice.

● Adenovirus infection. Runs with severe runny nose, sneezing, conjunctivitis. The eyes turn red, watery, there is pain and burning in the area of ​​​​the eyeballs and eyelids. Unlike other acute respiratory viral infections, adenovirus infection is often infected in spring and summer.

Other causes of fever:

● any infectious disease of a viral, bacterial, parasitic nature;

● non-infectious inflammations: acute pancreatitis, aspiration pneumonitis;

● allergic and autoimmune diseases: reaction to vaccination, rheumatoid arthritis, systemic lupus erythematosus;

● diseases of the thyroid gland, adrenal glands;

● oncological diseases: malignant tumors of internal organs, leukemia, lymphogranulomatosis;

● neurological pathologies: traumatic brain injury, cerebral hemorrhage;

● thermal (solar) stroke;

● psychogenic: prolonged emotional stress, neuroses, hysteria.

When temperature is dangerous

Fever poses a threat to health with a strong rise in temperature, when the thermometer shows 40˚C or more. This condition leads to dehydration, disruption of vital organs, and significantly increases the risk of thrombosis.

For healthy adults, an increase in temperature during SARS by 3˚C from the norm (36.6˚C) is not dangerous. However, for some people, even a febrile temperature can be harmful. At risk:

● Elderly people. After 65 years, it is more difficult for the body to adapt to an increase in temperature due to the age-related decrease in the ability to thermoregulate, the acquisition of chronic diseases.

● People with chronic diseases of internal organs: kidneys, cardiovascular, nervous system. Fever increases the load on these organs and can lead to an exacerbation of the disease.

What to do when the temperature is high

⁷

Fever helps to defeat the infection faster. With ARVI without fever, the infection takes longer, is accompanied by a pronounced deterioration in well-being, and is more often complicated. Therefore, it is worth suffering malaise for 2-3 days and not bringing down the temperature, provided that the body temperature does not exceed 38.5˚C. To make it easier to transfer the condition, avoid any physical activity, drink plenty of fluids, do not wrap yourself in blankets and excessively warm clothes that impair heat transfer.

But there are times when it is better to bring down the temperature:

● The thermometer reads over 39˚C.

● The rise in temperature is accompanied by a strong deterioration in the condition: loss of strength, poor sleep, nausea, vomiting.

● The patient is at risk.

Fever above 40˚C in adults requires emergency medical attention.

Non-drug methods. Wiping with a damp cloth or a weak vinegar solution will help to reduce the temperature. It is recommended to drink more warm drinks, such as tea with raspberry jam. Raspberries contain natural salicylates – substances that reduce fever. Drink should be moderately warm. Excessively hot or cold drinks and foods should be avoided.

Antipyretics. If non-drug remedies do not help, take antipyretics. The safest drugs are paracetamol-based, which can be taken even by small children and pregnant women. Paracetamol is included in most combined anti-cold complexes, which additionally relieve nasal congestion and symptoms of intoxication in acute respiratory viral infections.

Antivirals. Lowering the temperature is not an end in itself in the treatment of SARS. Antiviral therapy should fight the causative agent of the infection. To do this, develop specific antiviral drugs that prevent the reproduction of the virus and infection of healthy cells. In the treatment of colds and flu, enisamium iodide has proven itself well. Its use reduces the acute clinical manifestations of viral intoxication. ⁸

Enisamia iodide at a dosage of 500 mg is part of the drug Nobasit ^® Forte ⁸ . Nobasit ^® Forte begins to act within 2 hours after taking the tablet ^8. In addition to the direct antiviral effect, enisamia iodide has a pronounced anti-inflammatory activity ^{9, 10} . The combined action leads to a decrease in the severity of fever and other symptoms of intoxication (headache and muscle pain) by 3 times, starting from the second day of treatment ¹¹ . Also Nobasit ^® Forte helps to reduce the duration of the disease. ⁸

Briefly about the main

● Elevated is defined as a temperature above 37˚C measured in the armpit. If it is caused by an infection, this temperature is called a fever.

● The most common cause of fever in adults is SARS. Other causes – infections, non-infectious inflammation, heat stroke, stress, malignant tumors – are much less common.

● Fever brings recovery closer, but often it greatly affects well-being: it is accompanied by weakness, headache, body aches. In the elderly and people with common chronic diseases, fever often causes dangerous complications.

● Cool down in healthy adults should be above 38.5˚C and in at-risk people above 38˚C. If the temperature rises above 40˚C, it is worth calling an ambulance.

● First, try to bring down the temperature with home remedies – cool body wraps, tea with raspberry jam. If that doesn’t help, take an antipyretic medicine.

● Antipyretics will ease the fever but will not speed up recovery. To defeat the infection as soon as possible, take antiviral drugs, for example, Nobasit ^®
Forte.

¹ Tatochenko V.K., Uchaikin V.F. Fever // Pediatric pharmacology – 2006 – https://cyberleninka.ru/article/n/lihoradka

² Fugol D.S. An increase in body temperature in children and approaches to its correction // BC – No. 24, 2013 – https://elibrary.ru/item.asp?id=20603056

³ Vasilenko V.V. Measurement of body temperature // RMJ. – No. 29, 2008, S. 1948. https://www.rmj.ru/articles/istoriya_meditsiny/Izmerenie_temperatury_tela/

⁴ Dvovetsky L.I. Fever: to treat or not to treat // BC – No. 14, 2003 – https://www.rmj.ru/articles/obshchie-stati/Lihoradka_lechity_ili_ne_lechity/

⁵ Cheshik S.G., Vartanyan R.V. Respiratory syncytial viral infection: clinic, diagnosis, treatment // Children’s infections – No. 1, 2004 – https://cyberleninka.ru/article/n/respiratorno-sintsitialnaya-virusnaya-infektsiya-klinika-diagnosti…

⁶ Kalyuzhnaya L.I., Zemlyanoy D.A. Heat transfer disorders and fever // Pediatrician – T.6, No. 1, 2015 – https://cyberleninka.ru/article/n/narusheniya-teploobmena-i-lihoradka

⁷ Didkovsky N.A., Tanasova A.N. Fever. breast cancer. 2003; 4:189.

⁸ Instructions for medical use of the drug Nobasit® Forte LP-006416.