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Low grade fever diarrhea nausea: Viral gastroenteritis (stomach flu) – Symptoms & causes

Viral gastroenteritis (stomach flu) – Symptoms & causes


Viral gastroenteritis is an intestinal infection that includes signs and symptoms such as watery diarrhea, stomach cramps, nausea or vomiting, and sometimes fever.

The most common way to develop viral gastroenteritis — often called stomach flu — is through contact with an infected person or by consuming contaminated food or water. If you’re otherwise healthy, you’ll likely recover without complications. But for infants, older adults and people with compromised immune systems, viral gastroenteritis can be deadly.

There’s no effective treatment for viral gastroenteritis, so prevention is key. Avoid food and water that may be contaminated and wash your hands thoroughly and often.

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Although it’s commonly called stomach flu, gastroenteritis isn’t the same as influenza. The flu (influenza) affects only your respiratory system — your nose, throat and lungs. Gastroenteritis, on the other hand, attacks your intestines, causing signs and symptoms such as:

  • Watery, usually nonbloody diarrhea — bloody diarrhea usually means you have a different, more severe infection
  • Nausea, vomiting or both
  • Stomach cramps and pain
  • Occasional muscle aches or headache
  • Low-grade fever

Depending on the cause, viral gastroenteritis symptoms may appear within 1-3 days after you’re infected and can range from mild to severe. Symptoms usually last just a day or two, but occasionally they may last up to 14 days.

Because the symptoms are similar, it’s easy to confuse viral diarrhea with diarrhea caused by bacteria, such as Clostridioides difficile, salmonella and Escherichia coli, or parasites, such as giardia.

Viral gastroenteritis

The stomach, small intestine and large intestine (colon) are part of your digestive tract, which processes the foods you eat. Viral gastroenteritis is an inflammation of these organs caused by a virus.

When to see a doctor

If you’re an adult, call your health care provider if:

  • You’re not able to keep liquids down for 24 hours
  • You’ve been vomiting or having diarrhea for more than two days
  • You’re vomiting blood
  • You’re dehydrated — signs of dehydration include excessive thirst, dry mouth, deep yellow urine or little or no urine, and severe weakness, dizziness or lightheadedness
  • You notice blood in your bowel movements
  • You have severe stomach pain
  • You have a fever above 104 F (40 C)

For infants and children

See your child’s health care provider right away if your child:

  • Has a fever of 102 F (38.9 C) or higher
  • Seems tired or very irritable
  • Is in a lot of discomfort or pain
  • Has bloody diarrhea
  • Seems dehydrated — watch for signs of dehydration in sick infants and children by comparing how much they drink and urinate with how much is normal for them, and watching for signs such as a dry mouth, thirst and crying without tears

If you have an infant, remember that while spitting up may be an everyday occurrence for your baby, vomiting is not. Babies vomit for a variety of reasons, many of which may require medical attention.

Call your baby’s doctor right away if your baby:

  • Has vomiting that is frequent
  • Hasn’t had a wet diaper in six hours
  • Has bloody stools or severe diarrhea
  • Has a sunken soft spot (fontanel) on the top of his or her head
  • Has a dry mouth or cries without tears
  • Is unusually sleepy, drowsy or unresponsive


You’re most likely to get viral gastroenteritis when you eat or drink contaminated food or water. You may also be likely to get gastroenteritis if you share utensils, towels or food with someone who has one of the viruses that cause the condition.

Many viruses can cause gastroenteritis, including:

  • Noroviruses. Both children and adults are affected by noroviruses, the most common cause of foodborne illness worldwide. Norovirus infection can sweep through families and communities. It’s especially likely to spread among people in confined spaces.

    In most cases, you pick up the virus from contaminated food or water. But it can also spread between people who are in close contact or who share food. You can also get the virus by touching a surface that’s been contaminated with norovirus and then touching your mouth.

  • Rotavirus. Worldwide, this is the most common cause of viral gastroenteritis in children, who are usually infected when they put their fingers or other objects contaminated with the virus into their mouths. It can also spread through contaminated food. The infection is most severe in infants and young children.

    Adults infected with rotavirus may not have symptoms, but can still spread the illness. This is of particular concern in institutional settings such as nursing homes because adults with the virus unknowingly can pass the virus to others. A vaccine against viral gastroenteritis is available in some countries, including the United States, and appears to be effective in preventing the infection.

Some shellfish, especially raw or undercooked oysters, also can make you sick. Contaminated drinking water is a cause of viral diarrhea. But in many cases the virus is passed when someone with a virus handles food you eat without washing his or her hands after using the toilet.

Risk factors

Gastroenteritis occurs all over the world and can affect people of all ages.

People who may be more susceptible to gastroenteritis include:

  • Young children. Children in child care centers or elementary schools may be especially vulnerable because it takes time for a child’s immune system to mature.
  • Older adults. Adult immune systems tend to become less efficient later in life. Older adults in nursing homes are vulnerable because their immune systems weaken. They also live in close contact with others who may pass along germs.
  • Schoolchildren or dormitory residents. Anywhere that groups of people come together in close quarters can be an environment for an intestinal infection to get passed.
  • Anyone with a weakened immune system. If your resistance to infection is low — for instance, if your immune system is compromised by HIV/AIDS, chemotherapy or another medical condition — you may be especially at risk.

Each gastrointestinal virus has a season when it’s most active. If you live in the Northern Hemisphere, for instance, you’re more likely to have rotavirus or norovirus infections in the winter and spring.


The main complication of viral gastroenteritis is dehydration — a severe loss of water and essential salts and minerals. If you’re healthy and drink enough to replace fluids you lose from vomiting and diarrhea, dehydration shouldn’t be a problem.

Infants, older adults and people with weakened immune systems may become severely dehydrated when they lose more fluids than they can replace. Hospitalization might be needed so that lost fluids can be replaced through an IV in their arms. Dehydration can rarely lead to death.


The best way to prevent the spread of intestinal infections is to follow these precautions:

  • Get your child vaccinated. A vaccine against gastroenteritis caused by the rotavirus is available in some countries, including the United States. Given to children in the first year of life, the vaccine appears to be effective in preventing severe symptoms of this illness.
  • Wash your hands thoroughly. And make sure your children do, too. If your children are older, teach them to wash their hands, especially after using the toilet.

    Wash your hands after changing diapers and before preparing or eating food, too. It’s best to use warm water and soap and to rub hands well for at least 20 seconds. Wash around cuticles, beneath fingernails and in the creases of the hands. Then rinse thoroughly. Carry sanitizing wipes and hand sanitizer for times when soap and water aren’t available.

  • Use separate personal items around your home. Avoid sharing eating utensils, drinking glasses and plates. Use separate towels in the bathroom.
  • Prepare food safely. Wash all your fruits and vegetables before eating them. Clean kitchen surfaces before preparing food on them. Avoid preparing food if you’re sick.
  • Keep your distance. Avoid close contact with anyone who has the virus, if possible.
  • Disinfect hard surfaces. If someone in your home has viral gastroenteritis, disinfect hard surfaces, such as counters, faucets and doorknobs, with a mixture of 5-25 tablespoons (73 to 369 milliliters) of household bleach to 1 gallon (3.8 liters) of water.
  • Avoid touching laundry that may have been exposed to a virus. If someone in your home has viral gastroenteritis, wear gloves while touching laundry. Wash clothing and bedding in hot water and dry them on the hottest setting. Wash your hands well after touching laundry.
  • Check out your child care center. Make sure the center has separate rooms for changing diapers and preparing or serving food. The room with the diaper-changing table should have a sink as well as a sanitary way to dispose of diapers.

Take precautions when traveling

When you’re traveling in other countries, you can become sick from contaminated food or water. You may be able to reduce your risk by following these tips:

  • Drink only well-sealed bottled or carbonated water.
  • Avoid ice cubes because they may be made from contaminated water.
  • Use bottled water to brush your teeth.
  • Avoid raw food — including peeled fruits, raw vegetables and salads — that has been touched by human hands.
  • Avoid undercooked meat and fish.

More Information

Viral gastroenteritis (stomach flu) – Diagnosis & treatment


Your doctor will likely diagnose viral gastroenteritis (stomach flu) based on symptoms, a physical exam and sometimes on the presence of similar cases in your community. A rapid stool test can detect rotavirus or norovirus, but there are no quick tests for other viruses that cause gastroenteritis. In some cases, your doctor may have you submit a stool sample to rule out a possible bacterial or parasitic infection.


There’s often no specific medical treatment for viral gastroenteritis. Antibiotics aren’t effective against viruses. Treatment first involves self-care measures, such as staying hydrated.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

Self care

To help keep yourself more comfortable and prevent dehydration while you recover, try the following:

  • Let your stomach settle. Stop eating solid foods for a few hours.
  • Try sucking on ice chips or taking small sips of water often. You might also try drinking clear soda, clear broths or noncaffeinated sports drinks. In some cases you can try oral rehydration solutions. Drink plenty of liquid every day, taking small, frequent sips.
  • Ease back into eating. As you’re able, you can return to eating your normal diet. You might find that you can eat bland, easy-to-digest foods at first, such as soda crackers, soup, oats, noodles, bananas and rice. Stop eating if your nausea returns.
  • Avoid certain foods and substances until you feel better. These include caffeine, alcohol, nicotine, and fatty or highly seasoned foods.
  • Get plenty of rest. The illness and dehydration may have made you weak and tired.
  • Try anti-diarrhea medications. Some adults may find it helpful to take loperamide (Imodium A-D) or bismuth subsalicylate (Pepto-Bismol, others) to manage their symptoms. However, avoid these if you have bloody diarrhea or fever, which could be signs of another condition.

For infants and children

When your child has an intestinal infection, the most important goal is to replace lost fluids and salts. These suggestions may help:

  • Help your child rehydrate. Give your child an oral rehydration solution, available at pharmacies without a prescription. Talk to your doctor if you have questions about how to use it.

    Don’t give your child plain water — in children with gastroenteritis, water isn’t absorbed well and won’t adequately replace lost electrolytes. Avoid giving your child apple juice for rehydration — it can make diarrhea worse.

  • Get your child back to a normal diet once hydrated. Once your child is rehydrated, introduce him or her to his or her normal diet. This might include toast, yogurt, fruits and vegetables.
  • Avoid certain foods. Don’t give your child sugary foods, such as ice cream, sodas and candy. These can make diarrhea worse.
  • Make sure your child gets plenty of rest. The illness and dehydration may have made your child weak and tired.
  • Avoid giving your child store-bought anti-diarrheal medications, unless advised by your doctor. They can make it harder for your child’s body to get rid of the virus.

If you have a sick infant, let your baby’s stomach rest for 15-20 minutes after vomiting or a bout of diarrhea, then offer small amounts of liquid. If you’re breast-feeding, let your baby nurse. If your baby is bottle-fed, offer a small amount of an oral rehydration solution or regular formula. Don’t dilute your baby’s already-prepared formula.

Preparing for your appointment

If you or your child needs to see a doctor, you’ll likely see your doctor first. If there are questions about the diagnosis, your doctor may refer you to an infectious disease specialist.

What you can do

Preparing a list of questions will help you make the most of your time with your doctor. Some questions you might want to ask your or your child’s doctor include:

  • What’s the likely cause of the symptoms? Are there other possible causes?
  • Is there a need for tests?
  • What’s the best treatment approach? Are there any alternatives?
  • Is there a need to take medicine?
  • What can I do at home to ease the symptoms?

What to expect from your doctor

Some questions the doctor may ask include:

  • When did symptoms begin?
  • Have the symptoms been continuous, or do they come and go?
  • How severe are the symptoms?
  • What, if anything, seems to improve symptoms?
  • What, if anything, appears to worsen symptoms?
  • Have you been in contact with anyone with similar symptoms?

What you can do in the meantime

Drink plenty of fluids. As you’re able, you can return to eating your normal diet. You might find you can eat bland, easy-to-digest foods at first. If your child is sick, follow the same approach — offer plenty of fluids. When possible, start having your child eat his or her normal diet. If you’re breastfeeding or using formula, continue to feed your child as usual. Ask your child’s doctor if giving your child an oral rehydration solution, available without a prescription at pharmacies, would help.

Prolonged subfebrile condition – causes of the disease, which doctor treats, diagnosis, prevention and treatment


Prolonged subfebrile condition describes a condition when a person’s body temperature is kept below 38 ° C, but at the same time above the norm (about 36.6 ° C) over a long period of time, usually several weeks or months. Usually, subfebrile temperature can be noted during the day, especially in the evening, when it can rise to 37.2-37.5°C.

This condition may be accompanied by symptoms such as fatigue, headache, loss of appetite, weight loss, sweating and weakness. Although prolonged subfebrile condition is not necessarily a sign of any serious illness, it may indicate the presence of an underlying inflammatory process or other disease.

Possible causes of prolonged low-grade fever include: infections (eg, tuberculosis), diseases of the immune system (eg, rheumatoid arthritis), cancer, chronic inflammatory diseases (eg, Crohn’s disease), and stress and depression.

If you have a prolonged low-grade fever, it is recommended to see a doctor for diagnosis and treatment. The doctor may recommend various tests, such as blood tests, urine tests, x-rays, ultrasounds, and others, to identify the cause of the condition and determine the necessary treatment.

Why is prolonged low-grade fever dangerous? The cause of this condition can be serious, and if it is not detected and treated in time, various complications can occur, depending on the cause.

For example, if prolonged low-grade fever is caused by an infection, it can progress to more serious consequences such as sepsis or complications of the lungs, liver, or kidneys.

If the cause is a disease of the immune system, destruction of tissues and organs can occur, leading to complications of the corresponding disease.

Also, prolonged low-grade fever can be associated with stress and depression, which in turn can lead to other health problems, including cardiovascular disease and diseases of the digestive system.

Therefore, if you have prolonged low-grade fever, it is recommended that you see a doctor for diagnosis and treatment in order to rule out serious causes and prevent possible complications.

Physiological causes of prolonged subfebrile condition

Physiological causes of prolonged subfebrile condition may include:

  1. Periods of increased activity of the immune system, such as inflammation or tumor growth. In this case, subfebrile temperature can be caused by an increase in the production of cytokines, proteins that are involved in the regulation of the immune system and inflammatory processes.

  2. Menstrual cycle. In women, low-grade fever may occur before and during menstruation due to changes in hormone levels.

  3. Physical activity. With active training or heavy physical exertion, subfebrile temperature may be observed.

  4. Elevated ambient temperature. In hot weather or high humidity, body temperature may be slightly elevated.

  5. Early morning. For most people, body temperature can be slightly below normal in the early morning.

Although the physiological causes of prolonged low-grade fever may be harmless, if you notice such changes in body temperature, you should consult a doctor to rule out serious causes and complications.

Pathological causes of prolonged subfebrile condition

Pathological causes of prolonged subfebrile condition may be associated with various diseases and conditions, including:

  1. Chronic infections such as tuberculosis, brucellosis, cytomegalovirus infection, etc.

  2. Inflammatory diseases such as rheumatoid arthritis, systemic lupus erythematosus, etc.

  3. Various types of tumors, including lymphoma, leukemia, lung cancer, etc.

  4. Chronic liver diseases such as cirrhosis and hepatitis.

  5. Thyroid disorders such as hypothyroidism.

  6. Autoimmune diseases such as adult Still’s syndrome, systemic sclerosis, etc.

  7. Chronic bowel diseases such as ulcerative colitis, Crohn’s disease, etc.

  8. Hematopoietic disorders such as myelodysplastic syndrome, etc.

  9. Metabolic disorders such as diabetes mellitus and hyperthyroidism.

  10. Other diseases and conditions such as diseases of the nervous system, systemic diseases of the connective tissue, etc.

In any case, if you have a prolonged subfebrile condition, you need to see a doctor who can conduct an examination and prescribe the necessary treatment.

Accompanying symptoms

Accompanying symptoms of prolonged subfebrile condition depend on the cause of this condition. In general, in addition to elevated body temperature (usually up to 37.2-38 °C), the following symptoms may be observed:

  1. Fatigue and weakness

  2. Headache

  3. Pain in muscles and joints

  4. Loss of appetite

  5. Weight Loss

  6. Insomnia or excessive sleepiness

  7. Sore throat

  8. Cough

  9. Nasal congestion

  10. Digestive disorders such as nausea, vomiting, diarrhea or constipation.

If prolonged low-grade fever is associated with a chronic disease, specific symptoms characteristic of this disease may also be present. For example, with hepatitis, there may be jaundice and pain in the right upper quadrant of the abdomen, and with systemic lupus erythematosus, skin rashes and lesions of internal organs.

If you have prolonged low-grade fever with any additional symptoms, you should see a doctor for diagnosis and treatment.

What are the scenarios

Prolonged subfebrile condition can have different scenarios depending on its causes.

  1. Improved condition. If prolonged subfebrile condition is due to physiological causes, for example, fatigue or stress, then after the elimination of their effects, an improvement in the condition may occur. Also, if the infection has been treated adequately, the patient may also experience improvement.

  2. Status continuation. If prolonged low-grade fever is associated with a chronic disease, then this condition can continue for a long time. In this case, the patient may be offered treatment for the underlying disease and measures to reduce the temperature.

  3. Development of complications. If prolonged subfebrile condition is caused by an infection, then complications may develop, such as sepsis or meningitis. Therefore, with prolonged subfebrile condition, especially if it is accompanied by other symptoms, it is important to consult a doctor to identify the cause and prescribe the appropriate treatment.

  4. Development of new symptoms. Some diseases that can cause prolonged low-grade fever may lead to the development of new symptoms or complications over time. Therefore, it is important to monitor your condition and seek medical attention in a timely manner if new symptoms occur or existing ones worsen.

What diseases can cause prolonged subfebrile condition

Prolonged subfebrile condition can be associated with various diseases, including:

  1. Chronic infections such as tuberculosis, bronchitis, pneumonia, malaria, hepatitis and others.

  2. Autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, inflammatory myopathy, and others.

  3. Oncological diseases, including lymphoma, leukemia, sarcoma and others.

  4. Chronic bowel diseases such as gastric ulcer, duodenal ulcer, ulcerative colitis.

  5. Hormonal disorders, eg hypothyroidism.

  6. Chronic liver disease, eg cirrhosis of the liver.

  7. Rheumatic diseases, eg rheumatic fever.

  8. Other chronic diseases such as chronic heart failure, kidney disease, diabetes and others.

It is important to note that this list is not exhaustive, and prolonged low-grade fever may be associated with other diseases or factors, such as drug side effects or subclinical infection. In the presence of prolonged subfebrile condition, it is necessary to consult a doctor to identify the cause and prescribe the appropriate treatment.

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Kulikova Olga Alekseevna

Experience 10 years


What examinations to undergo

With prolonged subfebrile condition, the doctor may prescribe a number of examinations to identify the cause of the symptom. Depending on the preliminary diagnosis and clinical manifestations, the following tests may be prescribed:

  1. Complete blood count, which may show inflammation or infection.

  2. Blood chemistry, including liver function, kidney function, glucose and hormone levels.

  3. Urinalysis for infection or other abnormalities.

  4. Bacteriological examination such as sputum or feces for the presence of infectious agents.

  5. Immunological tests, for example, for autoantibodies in suspected autoimmune disease.

  6. X-ray examinations, such as a chest x-ray for suspected infection in the lungs.

  7. Ultrasound examination of the abdominal cavity and small pelvis.

  8. Computed tomography (CT) or magnetic resonance imaging (MRI) for suspected cancer.

All these studies will help to identify the cause of prolonged subfebrile condition and determine the necessary treatment. It is important to consult a doctor with prolonged low-grade fever so as not to miss a possible symptom of a serious illness.

How to remove

Prolonged subfebrile condition is a symptom, not an independent disease, therefore it must be treated by eliminating the underlying cause. Treatment will depend on the specific diagnosis.

For example, if prolonged low-grade fever is caused by a bacterial infection, a course of antibiotics may be required. If the cause is inflammation or an autoimmune disease, then anti-inflammatory drugs, glucocorticosteroids, or immunomodulators may be prescribed.

In some cases, prolonged subfebrile condition can be caused by a deficiency of vitamins or minerals. In such cases, the additional use of appropriate drugs can help eliminate the symptom.

In any case, self-medication is not recommended. If you have prolonged low-grade fever, it is important to see a doctor to determine the cause and prescribe the appropriate treatment.

Where to see a doctor

If you have a prolonged subfebrile condition, you should see a general practitioner. The therapist will conduct an examination, collect an anamnesis and determine further directions for examination and treatment. If necessary, the therapist may refer you to another specialist, such as an infectious disease specialist, gastroenterologist, rheumatologist, oncologist, etc., depending on the suspected cause of prolonged low-grade fever.

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What to do with a temperature without symptoms of the disease > Rubric in Samara

A temperature that does not differ much from the norm, but is already a sign of ill health, is usually called subfebrile in medicine.

In this situation, the thermometer may show 37.0 – 37.5°C for a long time. Sometimes the indicators can reach 37.9 ° C. If no other symptoms bother a person, doctors will have to conduct a series of additional tests to understand the cause. Prolonged subfebrile temperature is a special subject of study in therapeutic practice. Patients with such complaints come to the appointment quite often. According to statistics, in 70 – 80% of cases, protracted subfebrile condition occurs in young women with signs of asthenia, in those who suffer from increased fatigue, weakness, irritability, nervousness, have sleep disturbances and other psychopathological disorders. If the fever persists for more than a month or two, then a comprehensive examination is necessary.


Increased body temperature is caused by certain proteins – pyrogens. They can enter the body from the external environment or be produced spontaneously inside it. These proteins have a connection with the hypothalamus, activate the immune system and affect the general well-being of a person.

In some cases, subfebrile temperature may indicate that an infection with a disease has occurred. In others – about a malfunction in the body. Also, sometimes there are congenital pathologies that cause an increase in temperature.

Disorder of thermoregulation can serve as one of the signs of vegetovascular dystonia. With such a disease, a temperature often appears without symptoms of a cold. A person complains of heaviness in the head, weakness, pain. The heat in the body is abruptly replaced by chills. Cold palms and feet may indicate the local nature of thermoregulation failures. In most patients with dystonia, fever can persist for up to several months.

There are cases when low-grade fever causes an increase in the number of simple microbes, which in normal times are not dangerous. This is due to a weakened immune system. The reason for the increase in temperature can also be autoimmune processes, when the body’s defenses mistakenly begin to attack healthy tissue.

— In case of any increase in temperature, you should contact your local doctor. The specialist will first prescribe a general blood and urine test. Based on their results, he will decide on further examination and treatment. In general, absolutely any stress, including emotional stress, can affect the increase in body temperature. Oleg Fatenkov, chief therapist of the Samara region

In addition, doctors say that often a temperature of 37.0 – 37.5 ° C is a sign of an allergy of a latent or overt course. If the indicator reaches 38 ° C and lasts for a long time, then this can be a sign of serious diseases: bronchitis, sinusitis, tuberculosis, latent infections, tumor processes.

Subfebrile condition can also be caused by changes in temperature, stress, hormonal imbalance, and taking certain medications.

What to do?

In any case, a visit to a specialist is necessary. Do not try to bring down the temperature at home with drugs without the advice of a doctor.