What causes a fever of 103 degrees in adults. How to recognize high-grade fever symptoms. When should you worry about a high temperature in adults. What are the potential complications of untreated severe fevers. How is a high fever diagnosed and treated in adult patients.

Understanding Fever: What It Is and Why It Occurs

A fever is defined as an elevated body temperature, typically 100.4°F (38°C) or higher. It’s a common physiological response triggered by the body’s immune system to fight off infections or other underlying conditions. The hypothalamus, a part of the brain responsible for temperature regulation, resets the body’s internal thermostat to a higher level during a fever.

Why do fevers occur? The elevated temperature creates an inhospitable environment for many pathogens, making it harder for them to survive and reproduce. Additionally, a fever can enhance immune system function, accelerating the body’s defense mechanisms.

Normal Body Temperature Range

Contrary to popular belief, 98.6°F (37°C) is not the universal “normal” body temperature. Recent research suggests that average body temperatures have been gradually declining over the past two centuries. The current normal range is considered to be between 97°F (36.1°C) and 99°F (37.2°C).

• Factors affecting body temperature:
  • Time of day
  • Age
  • Physical activity
  • Hormonal fluctuations
  • Metabolic rate

High-Grade Fever in Adults: When Temperature Becomes Concerning

A high-grade fever in adults is generally considered to be 103°F (39.4°C) or higher. While lower-grade fevers are often manageable at home, high-grade fevers can be indicative of more serious underlying conditions and may require medical attention.

Are high-grade fevers always dangerous? Not necessarily. The severity of a fever doesn’t always correlate directly with the seriousness of the underlying condition. However, very high temperatures can lead to complications if left untreated.

Potential Complications of Untreated High Fevers

• Dehydration
• Hallucinations
• Seizures
• Organ damage (in extreme cases)

Common Causes of High Fever in Adults

High fevers in adults can be triggered by various factors, ranging from common infections to more serious medical conditions. Understanding these potential causes can help in determining when to seek medical attention.

Viral Infections

Viral infections are among the most common causes of fever in adults. These can include:

• Influenza (flu)
• COVID-19
• Common cold viruses
• Viral gastroenteritis (“stomach flu”)
• Viral pneumonia

Can a fully vaccinated person develop a high fever due to COVID-19? While breakthrough infections are possible, they typically result in milder symptoms, including lower-grade fevers, compared to infections in unvaccinated individuals.

Bacterial Infections

Bacterial infections can often lead to higher fevers than viral infections. Common bacterial causes include:

• Streptococcal infections (strep throat)
• Urinary tract infections (UTIs)
• Bacterial pneumonia
• Cellulitis
• Meningitis

Other Potential Causes

While infections are the most common culprits, other conditions can also result in high fevers:

• Autoimmune disorders (e.g., lupus, rheumatoid arthritis)
• Certain cancers (especially blood cancers like leukemia)
• Medications (drug fever)
• Heat exhaustion or heatstroke
• Thyroid storm (in hyperthyroidism)

Recognizing Symptoms Associated with High Fevers

While a fever can occur without other symptoms, it’s often accompanied by various signs that can help identify the underlying cause or severity of the condition.

Common Symptoms Accompanying High Fevers

• Chills and shivering
• Sweating
• Headache
• Muscle aches
• Fatigue and weakness
• Loss of appetite
• Dehydration

How can you differentiate between viral and bacterial infections based on symptoms? While it’s not always possible to distinguish between the two without medical tests, bacterial infections often cause more localized symptoms (like throat pain in strep throat) and may lead to higher fevers.

Red Flag Symptoms

Certain symptoms in conjunction with a high fever warrant immediate medical attention:

• Severe headache with neck stiffness
• Confusion or altered mental state
• Difficulty breathing
• Severe abdominal pain
• Seizures
• Rash that doesn’t blanch under pressure

When to Seek Medical Attention for a High Fever

While not all fevers require immediate medical intervention, certain circumstances call for professional evaluation. Understanding when to seek help can prevent potential complications and ensure timely treatment of underlying conditions.

General Guidelines for Adults

Consider seeking medical attention if:

• Your temperature reaches 103°F (39.4°C) or higher
• The fever persists for more than three days
• The fever doesn’t respond to over-the-counter fever reducers
• You have other concerning symptoms along with the fever

Special Considerations

Certain groups should seek medical attention more promptly:

• Older adults (65 years and above)
• Individuals with compromised immune systems
• People with chronic medical conditions (e.g., diabetes, heart disease)
• Recent travelers to areas with endemic infectious diseases
• Pregnant women

Should you go to the emergency room for a high fever? If the fever is accompanied by severe symptoms, such as difficulty breathing, chest pain, or altered mental state, emergency care may be necessary.

Diagnosing the Cause of High Fever in Adults

When a patient presents with a high fever, healthcare providers employ various diagnostic methods to determine the underlying cause and appropriate treatment plan.

Initial Assessment

The diagnostic process typically begins with:

• Detailed medical history
• Physical examination
• Accurate temperature measurement

What’s the most accurate way to measure body temperature in adults? While various methods exist, oral temperature measurement using a digital thermometer is generally considered the most accurate for adults when done correctly.

Laboratory Tests

Depending on the suspected cause, various tests may be ordered:

• Complete blood count (CBC)
• Blood cultures
• Urinalysis and urine culture
• Throat swab for strep test
• COVID-19 test
• Specific tests for suspected infections (e.g., malaria smear, tuberculosis tests)

Imaging Studies

In some cases, imaging may be necessary:

• Chest X-ray (for suspected pneumonia)
• CT scan (for suspected abscesses or other internal issues)
• MRI (in cases of suspected central nervous system involvement)

Treatment Approaches for High Fever in Adults

The treatment of high fever in adults focuses on addressing the underlying cause while managing symptoms and preventing complications. The approach can vary depending on the severity and origin of the fever.

Symptomatic Treatment

Initial management often involves:

• Antipyretic medications (fever reducers):
  • Acetaminophen (Tylenol)
  • Ibuprofen (Advil, Motrin)
• Adequate hydration
• Rest
• Cool compresses or lukewarm baths

Is it always necessary to treat a fever with medication? Not always. Mild to moderate fevers can actually help the body fight infection. However, high fevers or those causing significant discomfort may benefit from treatment.

Treating Underlying Causes

Specific treatments depend on the identified cause:

• Antibiotics for bacterial infections
• Antiviral medications for certain viral infections
• Antimalarial drugs for malaria
• Supportive care for viral infections without specific treatments
• Management of underlying conditions (e.g., autoimmune disorders, cancers)

Hospitalization

In severe cases or for high-risk individuals, hospitalization may be necessary for:

• Intravenous fluid administration
• Close monitoring of vital signs
• Intravenous antibiotics
• Management of complications

Preventing High Fevers and Associated Complications

While not all fevers are preventable, certain measures can reduce the risk of developing high fevers and associated complications.

Infection Prevention

• Practice good hygiene:
  • Regular handwashing
  • Proper food handling
  • Avoiding close contact with sick individuals
• Stay up to date with vaccinations
• Use insect repellent and take precautions in areas with mosquito-borne illnesses

Maintaining Overall Health

A healthy lifestyle can bolster your immune system:

• Balanced diet rich in fruits and vegetables
• Regular exercise
• Adequate sleep
• Stress management
• Limiting alcohol consumption
• Avoiding tobacco use

How does a strong immune system help prevent high fevers? A robust immune system can more effectively combat pathogens, potentially preventing infections or reducing their severity, which in turn may prevent high fevers.

Managing Chronic Conditions

For individuals with chronic health conditions:

• Adhere to prescribed treatment plans
• Attend regular check-ups
• Monitor your condition closely
• Communicate any changes or concerns to your healthcare provider promptly

Understanding the causes, symptoms, and appropriate responses to high fevers in adults is crucial for maintaining good health and preventing potential complications. While fevers are often a sign that your body is fighting an infection, high-grade fevers or those accompanied by concerning symptoms should not be ignored. By recognizing when to seek medical attention and taking preventive measures, you can better manage your health and reduce the risk of severe fever-related issues.

Fever & Temperature In Adults: When To Worry

Karen Justiniano, DO, MS, Stamford Health Medical Group

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A friend of mine whose father is 70 years old told me her story. It went something like this:

“My father never gets fevers. Out of nowhere the other day, he developed a 103 temperature with no other symptoms. He is also fully vaccinated against COVID-19. My mother brought him to the emergency room. Did she do the right thing, or would he likely have been fine if he stayed home and let the fever run its course?”

As a physician who cares for a variety of people with a variety of conditions, I have to say of course she did the right thing! When in doubt or when concerned, seeking medical attention is the smart thing to do.

But the longer answer is a little more complicated than that. It all starts with breaking down the purpose of a fever, and when you should truly worry. Please note—fevers in infants or young children are sometimes a different story—what you are about to read relates to adults only.

What is a fever and why do we get them, and sometimes with no other symptoms?

Fever is an elevated body temperature which means your temperature is 100.4 degree F or higher. A fever is the body’s way of fighting an infection by naturally raising your body’s temperature to “kill the germ.” The medical community likes to say that fever is a “good thing,” in most cases.

And yes, it’s completely possible for adults to develop a fever with no other symptoms, and for doctors to never truly find the cause. Viral Infections can commonly cause fevers, and such infections include COVID-19, cold or the flu, airway infection like bronchitis, or the classic stomach bug.

That’s why you often hear the word “viral” as an explanation because these types of infections often go away on their own after a few days.

What is considered a high fever in adults?

A high-grade fever in adults is 103 degrees F or higher.

Is it possible that a fever could be a sign of a “breakthrough case” of COVID-19 even if the person is fully vaccinated?

Yes, but not highly likely. Breakthrough cases of COVID-19 in fully vaccinated people have been reported, but symptoms tend to be milder than in non-vaccinated people, including fever.

First, make sure you are taking your temperature the right way. Taking your temperature by mouth is the most accurate method, and wait at least 30 minutes after you eat or drink anything hot or cold. Get medical attention for your fever if:

• Your temperature is high and has not gone down after taking Tylenol or Advil
• Your temperature lasts several days or keeps coming back
• You live in an area where people have COVID-19
• You have serious health conditions like diabetes, heart disease, cancer, lupus, or sickle cell anemia. (Non-infections like these can cause fever as well.)

You should also seek medial attention if you have a fever and you:

• Are pregnant
• Recently returned from travel overseas
• Get infections often
• Are on chemotherapy, in which case you should seek medical attention immediately if the fever lasts for more than one hour.
• Have recently been bitten by a tick

Is 98.6 still considered “normal” body temperature?

Yes and no. You’ve probably always heard that the average body temperature is 98.6, but the truth is there’s a much wider range—from about 97 to 99 degrees F.

So why is 98.6 suddenly a myth after all these centuries? Research suggests body temperatures are falling overall. Doctors have a few ideas about why this is, including lower metabolic rates, lower rates of infection and more advanced thermometers.

A couple of helpful reminders:

1. As the saying goes, “Don’t fear the fever.” A fever is your body’s first line of defense in fighting off an infection.
2. If you are not fully vaccinated against COVID-19, and have developed a high-grade fever, please call your doctor right away.

High Temperature Causes and Treatments

Written by Rick Ansorge

• What Is a Fever?
• Fever Symptoms
• Fever Causes
• Fever Diagnosis
• Fever Treatments

A fever is a body temperature that’s higher than is considered normal. It’s also called a high temperature, hyperthermia, or pyrexia, and it’s usually a sign that your body is working to keep you healthy from an infection. Normal body temperatures are different for everyone, but they lie within the range of 97 to 99. A temperature of 100.4 or higher is considered a fever.

A part of your brain called the hypothalamus controls your body temperature. In response to an infection, illness, or some other cause, the hypothalamus may reset the body to a higher temperature. So when a fever comes on, it’s a sign that something is going on in your body.

Fevers themselves generally aren’t dangerous, but you should check in with your doctor if:

• An adult’s temperature is 103 or higher
• A very young infant (under 3 months) has a rectal temperature 100.4 or higher (call your doctor or go to an emergency room immediately)
• A 3-6-month-old has a higher than normal rectal temperature and is also irritable or sleepy (call your doctor right away)
• A 3-6-month-old has a 102 or higher rectal temperature
• A 6-24-month-old has a fever higher than 102 for more than a day or with other symptoms such as a cough or diarrhea
• A child older than 2 has a fever that comes with rash, real discomfort, irritability, listlessness, headache, stiff neck, or repeated diarrhea or vomiting
• An infant or child has a seizure
• Any temperature over 104 in a child, which could cause a seizure
• Any fever that starts after someone has been in hot temperatures, which could be a sign of heat stroke
• The fever doesn’t go down after taking over-the-counter medications such as ibuprofen in the appropriate doses
• You’ve been in contact with someone who has COVID-19

Fevers are signs of some sort of illness or infection. When you have, you may also notice these symptoms:

• Chills or shivering
• Sweating
• Headache
• Feeling weak
• Being irritable
• Losing your appetite
• Being dehydrated

A fever can be a sign of several health conditions, which may or may not need medical treatment.

The most common causes of fever are infections such as colds and stomach bugs (gastroenteritis). Other causes include:

• Infections of the ear, lung, skin, throat, bladder, or kidney
• Heat exhaustion
• COVID-19
• Sunburn
• Conditions that cause inflammation, such as rheumatoid arthritis
• Side effects of medications
• Vaccines and immunizations
• Blood clots
• Autoimmune conditions such as lupus and inflammatory bowel disease (IBS)
• Cancer
• Hormone disorders such as hyperthyroidism
• Illegal drugs such as amphetamines and cocaine
• Teething in babies can cause a mild, low-grade fever (not over 101 degrees)

Although a fever is easy to measure with a thermometer, finding its cause can be hard. Besides a physical exam, your doctor will ask about symptoms and conditions, medications, and if you’ve recently traveled to areas with infections or have other infection risks. A malaria infection, for example, may cause a fever that typically comes back. Some areas of the U.S. are hot spots for infections such as Lyme disease and Rocky Mountain spotted fever.

Your doctor may ask if you have been around someone with COVID-19 or have any other symptoms of COVID-19.

Sometimes, you may have a “fever of unknown origin.” In such cases, the cause could be an unusual or not obvious condition such as a chronic infection, a connective tissue disorder, cancer, or another problem.

Fever is usually associated with physical discomfort, and most people feel better when a fever is treated. But depending on your age, physical condition, and the underlying cause of your fever, you may or may not require medical treatment for the fever alone. Many experts believe that fever is a natural bodily defense against infection. There are also many non-infectious causes of fever.

Treatments vary depending on the cause of the fever. For example, antibiotics would be used for a bacterial infection such as strep throat.

The most common treatments for fever include over-the-counter drugs such as acetaminophen and nonsteroidal anti-inflammatory drugs such as ibuprofen and naproxen. Children and teens should not take aspirin because it’s linked to a condition called Reye’s syndrome.

Stay comfortable by: 

• Drinking a lot of clear liquids such as water, broth, and juices or a rehydration drink.
• Taking a lukewarm bath.
• Resting.
• Keeping yourself cool with lightweight clothing and bed coverings.

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Fever – Humanitas

Fever is usually a signal that something is wrong in the body. In an adult, fever is accompanied by malaise, however, as a rule, a temperature increase of no more than 103 F (39.4 C) is considered harmless. In children of the first days of life and infants, even a slight increase in temperature may indicate the presence of a serious infection.

However, the severity of the fever does not always indicate the severity of the underlying condition. A mild illness may cause a fever with a significant increase in temperature, and a severe illness may be accompanied by a slight increase in temperature.

The fever usually resolves within a few days. A number of over-the-counter drugs can lower a fever, but in some cases it is better not to lower it. An increase in body temperature greatly contributes to the body’s fight against a number of infectious diseases.

Symptoms

Fever is an increase in temperature above normal values. The temperature normal for an individual may be slightly above or below the average normal temperature 98. 6 F (37 C).

Fever, depending on the cause, may be accompanied by signs and symptoms such as:

• Sweating
• Trembling
• Headache
• Muscle pain
• Loss of appetite
• Dehydration
• General weakness

Fever 103 F (39.4 C) to 106 F (41.1 C) may cause:

• Hallucinations
• Confusion
• Irritability
• Convulsions
• Dehydration

Conditions requiring medical attention

Fever in itself is not a cause for concern and a reason to seek medical attention. However, there are times when, if you have a fever, you need to see a doctor yourself or take your child to the doctor.

Temperature measurement

Several types of thermometers are suitable for taking your own and your baby’s temperature, including oral, rectal, and ear (tympanic) thermometers.

Although not the most accurate method, an oral thermometer can be used to measure armpit temperature (axillary temperature).

• Place the thermometer in the armpit and cross your arms over your chest.
• Wait four or five minutes. Axillary temperature is slightly lower than oral.
• The doctor who came on call must be informed of the actual readings of the thermometer and name the place where the temperature was taken.

A rectal thermometer is suitable for measuring temperature in young children:

• To do this, grease the bulb of the thermometer with petroleum jelly.
• Place the baby on the stomach.
• Carefully insert the bulb of the thermometer half a centimeter into the child’s rectum.
• Hold the thermometer and child still for three minutes.
• Never let go of the thermometer while it is in the child’s body. If the child wriggles, the thermometer may go deeper and cause damage.

Infants

Unlike adults, unexplained fever in children is a serious cause for concern. If your child’s temperature rises to 101 F (38. 3 C) or more, contact your pediatrician. You should also call a doctor in the following cases:

• Fever in a child under 3 months old.
• Refusal of the child to eat and drink.
• Fever and unexplained irritability: the child cries a lot, for example when changing a diaper or at the slightest movement.
• Lethargy and lack of reaction in a child with fever. In infants and children under 2 years of age, these signs may be signs of meningitis, an infection and inflammation of the membranes and fluid surrounding the brain and spinal cord. If meningitis is suspected, the child should be seen by a doctor immediately.
• The body temperature of the newborn is below normal – below 97 F (36.1 C). In the youngest children, during illness, body temperature is difficult to regulate: it may fall rather than rise.

Children

If a child has a fever, but still reacts to others: makes eye contact, responds to facial expressions and voice, then there is probably nothing to worry about.

In the following cases, the child should be taken to the doctor:

• Lethargy or irritability, frequent vomiting, severe headaches or abdominal pain, or any other symptoms that cause severe discomfort.
• Fever after being in a hot car. Seek immediate medical attention if:
• Fever persists for more than one day (in children under 2 years of age) or more than three days (in children 2 years of age and older)

In special cases, for example, if the child has diseases associated with disorders of the immune system or any pre-existing diseases. Doctors also advise caution if a child has recently been prescribed a new drug.

Adults

Seek medical attention if:

• Temperature rises above 103 F (39.4 C)
• Persistence of fever for more than three days

In addition, seek immediate medical attention if any of the following signs or symptoms accompany a fever:

• Severe headache
• Severe swelling of the throat
• Unusual skin rash, especially if it progresses rapidly
• Unusual sensitivity to bright light
• Stiff neck and pain when bending head forward
• Confusion
• Prolonged vomiting
• Labored breathing or chest pain
• Extreme lethargy or excitability
• Abdominal pain or pain when urinating
• Other unexplained signs and symptoms

Complications

Fever may be accompanied by the following complications:

• Severe dehydration
• Hallucinations
• Fever-induced convulsions (febrile convulsions) in a small number of children aged 6 months to 5 years
• Febrile convulsions

Febrile seizures are usually accompanied by loss of consciousness and convulsions of the limbs, involving muscle groups on both sides of the body. Although febrile seizures are a cause of concern for parents, in most cases they do not have any long-term consequences.

If ​​a febrile seizure occurs:

• Place the child on its side or stomach on the floor or other flat surface
• Remove all sharp objects within reach of the child
• Rid the child of tight clothing
• Hold the child to avoid injury.

Do not put anything in the child’s mouth or try to stop seizures
In most cases, seizures go away on their own. After the seizures stop, it is necessary to show the child to the doctor as soon as possible to determine the cause of the fever.

If convulsions persist for more than 10 minutes, seek emergency medical attention.

high temperature, what to do?

High temperature is an increase in body temperature above normal values. Normal body temperature in the armpit is 36.0-36.9ºС, and in the morning it is 0.3-0.5ºС lower than in the evening. In the oral cavity and rectum, the temperature is usually 0.5-1 ºС higher than in the armpit, but does not exceed 37.5 ºС.

The causes of fever are manifold. The most common of these are infectious diseases. Microorganisms, their toxins and waste products affect the thermoregulatory center in the brain, causing an increase in body temperature.

There are several types of fever. According to the degree of temperature rise, subfebrile is distinguished – not higher than 37.5ºС; and febrile fever. Everyone is familiar with the manifestations of fever: muscle aches, headache, pain in the eyes, weakness, chills. Chills are nothing more than a physiological way to increase body temperature. When muscles contract, they increase heat production, and body temperature rises.

An increase in body temperature during an infectious disease does not occur by chance. Fever has important physiological significance. First, many bacteria die at high temperatures or lose their ability to reproduce. In addition, with an increase in body temperature, the body’s defense mechanisms to fight infection increase. Therefore, if the fever is benign and there are no other symptoms, drug treatment is usually not required – plentiful warm drinking and rest are recommended.

However, there are negative consequences of fever. In addition to subjectively unpleasant sensations, fever leads to increased fluid loss and excessive energy expenditure, which can be dangerous in people suffering from cardiovascular and other chronic diseases. High fever is especially dangerous for children who have an increased tendency to convulsions.

When should the temperature be lowered?

• For severe discomfort.
• Sleep disorders.
• When the temperature rises above 38.5°C.

Tips for lowering the temperature:

The room should not be too hot and should be ventilated regularly. Do not rub the patient’s skin with alcohol – this can increase the chills.