A low-grade fever is usually defined as a body temperature between 99 F (37.2 C) and 100.3 F (37.9 C). Some healthcare providers define a low-grade fever as a body temperature between 100 F (37.8 C) and 102 F (38.9 C).
A normal body temperature is about 98.6 F (37 C), with slight variations also considered normal in healthy people. These minor changes may be due to several factors, such as whether the temp is taken orally or rectally, or in the morning or the evening.
This article explains low-grade fever symptoms associated with a number of infections or other possible causes. It offers tips on how to manage a fever and how to know when to call a healthcare provider.
Low-Grade Fever Symptoms
Outside of an elevated body temperature in the range described above, some people with a low-grade fever won’t have any noticeable symptoms. Others may experience:
- Muscle aches
- Loss of appetite
- Lower urine output
Most low-grade fevers run their course in a few days and don’t require medical attention.
A low-grade fever is generally not cause for concern unless it is persistent and/or accompanied by other, more serious symptoms, like vomiting or pain.
What Causes a Low-Grade Fever?
A fever—even a low-grade one—is a sign that something is wrong with your body. It indicates that your immune system is mounting a defense against a foreign invader, be it a virus, bacterium, or other matter.
Experts aren’t exactly sure why the body responds to infections and illnesses with a raised body temperature, but they think some disease-causing germs are less likely to thrive in higher temperatures.
Experts also theorize that increased body temperatures might better enable certain immune cells to seek out and destroy whatever is attacking the body.
How the Immune System Keeps You Healthy
Both viral and bacterial infections can cause low-grade fevers. Some common culprits include:
- Rhinoviruses (aka the common cold)
- Chickenpox (varicella-zoster virus)
- Rubella (also called German measles)
- Urinary tract infections
- Ear infections
- Strep throat
- Cellulitis, an infection of the skin and the tissues around it
- Sinus infections
Other common causes include:
- Infectious mononucleosis (mono), a highly contagious illness that usually affects teens and young adults. It’s often caused by infection with the Epstein-Barr virus.
- Viral gastroenteritis (otherwise known as the stomach flu). Examples of these include the rotavirus, common in babies, and norovirus, which generally affects adults and is highly contagious.
- Escherichia coli (E. coli), a bacterial infection. Some strains of E.coli that live in the intestines are harmless, while others can produce serious illness.
An Overview of E. Coli
Certain autoimmune diseases, such as rheumatoid arthritis and lupus, can display a low-grade fever. In fact, up to 86% of people with lupus experience fever, usually a low-grade one.
Some malignant tumors (cancers) can cause cellular changes in the body that produce fevers. What’s more, the chemotherapy used to treat some cancers can destroy your body’s disease-fighting white blood cells, making you more susceptible to infections and the fevers that come with them.
Other causes of low-grade fever include:
- Stress: Stress causes low-grade fever in some people. Young women, notably, respond to stress with higher core body temperatures. This is known as psychogenic fever.
- Vaccines: Low-grade fever is a common side effect of many vaccines, including the flu shot and childhood immunizations. The fever is a sign your body is building immunity to the disease.
- Sensitivity to certain drugs: Some fevers can be attributed to adverse reactions to certain drugs, including antibiotics and drugs that treat seizures. These "drug fevers" have been seen during treatment of COVID-19, and with certain cancer treatments.
- Menstruation: Research shows an increase in basal body temperature of between 0.3 C and 0.7 C (roughly about 0.4 F) during and immediately after ovulation.
Persistent Low-Grade Fever
A persistent low-grade fever doesn't go away or recurs intermittently over a period of weeks.
If the temperature is equal to or higher than 101 F(38.3 C) without explanation, it may be called a fever of unknown origin (FUO). This can be a sign of a serious condition, including certain cancers.
In some cases, you may have a fever and no other symptoms. Contact your healthcare provider to diagnose a persistent low-grade fever in adults or children.
Causes of Fevers
Taking a Temperature
You may look flushed and feel warm when you have a fever, but the only way to accurately know your temperature is to measure it with a thermometer.
Digital thermometers, placed under the tongue or with the tip inserted into the anus (rectal temperature-taking is recommended for babies and very young children) offer the most reliable readings.
Don't relay on touch when trying to figure out if you or someone else has a fever. This method can cause you to miss or underestimate fever. This happens in up to 40% of people, even when the fever is as high as 102 F (38.9 C).
Thermometers placed under the armpit (called axillary) can give inaccurate readings. The same is true for plastic strip, smartphone temperature apps, and pacifier thermometers.
Thermometers that scan the forehead or are placed inside the ear (called tympanic) are OK to use, but don't use a tympanic thermometer if you're taking the temperature of baby younger than 3 months of age or anyone with an ear infection.
How to Use a Thermometer to Check for Fever
The general rule of thumb is to treat a low-grade fever only if it’s causing you discomfort. And some experts say that doesn’t happen until a temperature hits 102 F (38.9 C) to 103 F (39.4 C) and higher.
There’s also a pretty vocal school of thought that says when you suppress a fever, you also suppress the immune system’s production of disease-busting white blood cells, thereby prolonging the illness.
When you want to treat a low-grade fever, Tylenol (acetaminophen) and Advil (ibuprofen) are good choices. Follow the package directions for proper dosage, or ask your healthcare provider.
Aspirin is another option, but never give aspirin to children or teens unless instructed by your healthcare provider. Aspirin use in this age group has been associated with a serious and potentially deadly disorder called Reye’s syndrome.
Self-help measures include:
- Staying hydrated, because fevers can cause dehydration as your body loses water through sweating or rapid breathing
- Wearing light clothing
- Eating light, easy-to-digest foods, such as broth-based soups
Should I Go to Work With a Fever of 99 Degrees?
If you can stay home, it's probably best you do. That's especially true if you don't yet know what's causing the fever or if your illness is contagious. The Centers for Disease Control and Prevention (CDC) urges all workers with a fever of 100 F (37.8 C) to stay home for at least 24 hours after a fever is gone.
How Fever Is Treated
When to Should I Be Concerned About a Low-Grade Fever?
Call your healthcare provider or make a trip to the emergency room if any of the following apply to you or someone you’re caring for:
- You have a baby under 3 months of age with any fever. Don’t give fever-reducing medicines, such as Infants’ Tylenol, without consulting your healthcare provider.
- You have a fever and a stiff neck. This is a symptom of a life-threatening condition called meningitis, which affects the brain and spinal cord.
- You have a fever and a rash. The two combined can indicate some serious conditions, such as toxic shock syndrome and Rocky Mountain spotted fever.
- You’re feeling dehydrated. Signs include dry mouth, dry skin, sunken eyes and dark urine.
- Your child has a fever and experiences a seizure. Fevers—especially ones that rise quickly—can sometimes trigger what’s known as febrile seizures in young children.
- You feel very sick. For example, you're unable to get out of bed.
- You have a fever and severe pain or inflammation anywhere in your body.
- You have pain when you urinate or your urine is foul-smelling. This may be a sign of a urinary tract infection (UTI) that needs treatment with an antibiotic.
- You’re disoriented. You may feel dizzy, lightheaded, or even experience hallucinations.
- It won't go away. A fever that lasts more than two days is a sign you need to be evaluated.
Fevers of any kind can be stressful. But it’s important to remember that most low-grade fevers are harmless and run their course in a few days or less. Call your healthcare provider if you’re worried about symptoms or simply want to ask for advice and reassurance.
Frequently Asked Questions
What is considered a low-grade fever for babies and children?
For children, a low-grade fever is a temperature between 99 F (37.2 C) and 100.3 F (37.9 C). If your infant is 3 months old or younger, call your doctor for any fever, even a low-grade one. Mild fevers can sometimes indicate a serious infection in very young babies.
Can low-grade fever be the only symptom of COVID-19?
Some people with COVID-19 have a low-grade temperature of 100.3 F (37.9 C) or less. Most people will also have other symptoms, though, such as a sore throat, cough, or fatigue. It's also possible to have no fever, especially in the first few days of being infected.
Learn More:Symptoms of COVID-19
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Cedars Sinai. Fever.
Seattle Children’s. Fever — myths versus facts.
Walter EJ, Hanna-Jumma S, Carraretto M, Forni L. The pathophysiological basis and consequences of fever. Critical Care. 2016;20:200. doi:10.1186/s13054-016-1375-5
The Ohio State Wexner Medical Center. Is normal body temperature no longer 98.6.
Timlin H, Syed A, Haque U, Adler B, Law G, Machireddy K, Manno R. Fevers in adult lupus patients. Cureus. 2018;10(1):e2098. doi:10.7759/cureus.2098
Oka T. Psychogenic fever: how psychological stress affects body temperature in the clinical population. Temperature. 2015;2(3). doi:10.1080/23328940.2015.1056907
Zhang X, Zhao M, Zheng C. Drug fever induced by carboplatin-based regimens: Higher incidence in a women's hospital. Taiwan J Obstet Gynecol. 2021 Sep;60(5):882-887. doi:10.1016/j.tjog.2021.07.018.
Baker FC, Siboza F, Fuller A. Temperature regulation in women: Effects of the menstrual cycle. Temperature (Austin). 2020 Mar 22;7(3):226-262. doi:10.1080/23328940.2020.1735927.
Batra P, Saha A, Faridi MM. Thermometry in children.J Emerg Trauma Shock. 2012;5(3):246-249. doi:10.4103/0974-2700.99699
Nemours. How to take your child's temperature.
Centers for Disease Control and Prevention. Stay Home When You Are Sick.
Seattle Children’s. Fever (0-12 Months).
John Hopkins Medicine. Coronavirus symptoms: Frequently asked questions.
Del Bene VE. Clinical Methods: The history, physical, and laboratory examinations. Chapter 218: Temperature.(3rd edition). Boston: Butterworths.
By Donna Christiano Campisano
Donna Christiano is an award-winning journalist, specializing in women and children's health issues. She has been published in national consumer magazines and writes frequently for leading health websites.
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Is 99 a low-grade fever? ›
Some experts define a low-grade fever as a temperature that falls between 99.5°F (37.5°C) and 100.3°F (38.3°C). According to the U.S. Centers for Disease Control and Prevention (CDC), a person with temperature at or above 100.4°F (38°C) is considered to have a fever.Is a 99.1 a fever? ›
An adult probably has a fever when the temperature is above 99°F to 99.5°F (37.2°C to 37.5°C), depending on the time of day.Should I go to work with a fever of 99? ›
All employees should stay home if they are sick until at least 24 hours after their fever* (temperature of 100 degrees Fahrenheit or 37.8 degrees Celsius or higher) is gone. Temperature should be measured without the use of fever-reducing medicines (medicines that contains ibuprofen or acetaminophen).What is now considered a low-grade fever? ›
While body temperatures vary, most of us have an internal temperature around 98.6 degrees Fahrenheit. A temperature slightly higher than that is still normal. When your temperature is between 100.4 and 102.2, you have what is considered a low grade fever.What is the temperature range for Covid? ›
People with these symptoms or combinations of symptoms may have COVID-19: Fever greater than 99.9F or chills. Cough. Shortness of breath or difficulty breathing.How do you get rid of a 99 fever? ›
- Take your temperature and assess your symptoms. ...
- Stay in bed and rest.
- Keep hydrated. ...
- Take over-the-counter medications like acetaminophen and ibuprofen to reduce fever. ...
- Stay cool. ...
- Take tepid baths or using cold compresses to make you more comfortable.
Symptoms may appear 2-14 days after exposure to the virus. Anyone can have mild to severe symptoms. Possible symptoms include: Fever or chills.Why do I feel hot but no fever? ›
It's possible to feel feverish but not be running an actual temperature. Underlying medical conditions, hormone fluctuations, and lifestyle may all contribute to these feelings. Feeling feverish or hot may be one of the first signs of having a fever. But sometimes you may feel like you have a fever when you do not.Why do I have a low-grade fever but feel fine? ›
Long lasting low-grade fevers can occur with viral or bacterial infections, stress, or certain medications. Other health conditions like thyroid issues or autoimmune diseases can also cause this symptom.Is a low-grade fever contagious? ›
It may seem harmless enough, but assume any fever is a symptom of a contagious condition. Viruses that cause fevers are contagious as long as the fever is above a 100.4 degrees Fahrenheit reading rectally.
Should I go to work with 99.2 fever? ›
Zeigler said it's okay to head to work with a low-grade fever if you don't have any other symptoms. “Some low-grade fevers can be easily treated with over-the-counter medications and it would be fine to work,” explained Zeigler.How do you break a fever? ›
- Drink plenty of fluids. ...
- Take a lukewarm bath or shower. ...
- Use damp cloths on your forehead, neck, feet, and hands. ...
- Dress lightly and keep cool. ...
- Take ibuprofen or acetaminophen. ...
- Use a fan to cool off. ...
- Increase indoor humidity. ...
- Place a cold compress on your head.
Low body temperature and illness. Certain illnesses, or incorrect temperature readings, could factor into why your thermometer reads 96°F (35.55°C), but you feel sick. Low body temperature could also be a symptom of a serious illness like hypothermia or sepsis, but you'd likely have severe symptoms.Should I treat a low-grade fever? ›
Medication isn't needed. Call the doctor if the fever is accompanied by a severe headache, stiff neck, shortness of breath, or other unusual signs or symptoms. If you're uncomfortable, take acetaminophen (Tylenol, others), ibuprofen (Advil, Motrin IB, others) or aspirin.Can low-grade fever go away on its own? ›
A low-grade fever is mild and usually settles on its own. Over-the-counter (OTC) medication can help to lower a fever, however, it is good to let go a low-grade fever with adequate rest and plenty of fluids.Why do fevers spike at night? ›
Cortisol is higher during the day, and these higher levels suppress your immune activity to a large degree. When cortisol levels go down at night, your immune system is more active in fighting illness or infection. This is why fevers spike at night.Can you run a low-grade fever with COVID-19? ›
Many people with the disease run a low-grade fever for days, she said, and some may have no fever at all. Upper respiratory tract symptoms including sore throat, nasal congestion, and a runny nose have seemed more common with the current omicron variant of COVID-19.Is COVID-19 a cold or fever? ›
Symptom check: Is it COVID-19 or a cold?
|Runny or stuffy nose||Usually||Usually|
Air conditioning lowers our core body temperature
The system only works up to a point though—when your body temperature rises above 39°C, you're experiencing a high fever and can develop hyperthermia, which makes a cooling mechanism such as air conditioning vital for staying safe and healthy.
- Sit in a bath of lukewarm water, which will feel cool when you have a fever. ...
- Give yourself a sponge bath with lukewarm water.
- Wear light pajamas or clothing.
- Try to avoid using too many extra blankets when you have chills.
- Drink plenty of cool or room-temperature water.
- Eat popsicles.
How long can a low-grade fever last? ›
Most low-grade fevers go away without medical intervention after 1 to 3 days, but a persistent or chronic fever may last or keep coming back for more than 10 days.When is COVID not contagious? ›
Everyone's immune response is different, and we can spread the virus for different amounts of time. Masking on days 6-10 helps reduce the risk that we will get others sick after recovering from COVID-19. Most people are no longer infectious after day 10.How long are you infectious with COVID? ›
The COVID-19 infectious period can vary, but most people are considered infectious from 48 hours before their symptoms start and can be infectious for up to 10 days.Do you feel worse day 7 of COVID? ›
After you test positive for COVID-19
Some people get worse again after they first start to feel a bit better. This usually happens about 7 to 10 days after their symptoms started. You might have mild symptoms and feel unwell for a short time before slowly starting to feel better.
- Flushed face.
- Hot, dry skin.
- Chills and shivering.
- Muscle aches.
- Loss of appetite.
Call your health care provider if your temperature is 103 F (39.4 C) or higher. Seek immediate medical attention if any of these signs or symptoms accompanies a fever: Severe headache. Rash.Can you have a fever but feel hot instead of cold? ›
If you have a fever, you may experience these symptoms: Feel warm to the touch. Because a fever causes a rise in your body temperature, it may make your skin feel hot and sweaty. Warm skin is common with fevers.How do I know if my fever is viral or bacterial? ›
- Symptoms persist longer than the expected 10-14 days a virus tends to last.
- Fever is higher than one might typically expect from a virus.
- Fever gets worse a few days into the illness rather than improving.
Most fevers usually go away by themselves after 1 to 3 days. A persistent or recurrent fever may last or keep coming back for up to 14 days. A fever that lasts longer than normal may be serious even if it is only a slight fever.What causes a fever but not contagious? ›
Noncontagious causes of fever include urinary tract infections, ear infections, and causes unrelated to infections. The most common cause of fever is a viral upper respiratory infection (the common cold).
Is low-grade fever viral or bacterial? ›
Fevers are often a sign that your body is fighting off some type of bacterial or viral infection. A viral fever is any fever that's caused by an underlying viral illness. A variety of viral infections can affect humans, from the common cold to the flu. A low-grade fever is a symptom of many viral infections.What does COVID sore throat feel like? ›
Some people describe COVID sore throat as the most painful sore throat they've ever experienced. Others report a sore throat that isn't too different from one caused by a regular cold. Other COVID sore throat symptoms people notice include: Pain when swallowing or talking.Can you go to school with a 99.5 temp? ›
Fever: Students should not be present in school if their temperature is greater than 100 degrees Farenheit. In order to return to school, temperature should be below 100 degrees Farenheit for 24 hours without the help of fever-reducing medicine (i.e., Tylenol, ibuprofen).Should I use blankets with a fever? ›
Dress light. Bundling up too much can make it harder to reduce a fever. If you have chills, try wearing a single, light layer and using one lightweight blanket. If your temperature's over 103ºF, let your doctor know.Does Tylenol break a fever? ›
Acetaminophen: Take any one of the acetaminophen products: Tylenol, Anacin-3, Panadol, or Tempra. The dosage is 2 tablets (650 mg) every 4 to 6 hours. 2 hours after they are taken, these drugs will reduce the fever 2° to 3°F (1° to 1.5° C).Do you feel sick with a low-grade fever? ›
Outside of an elevated body temperature in the range described above, some people with a low-grade fever won't have any noticeable symptoms. Others may experience: Headache. Fatigue.What temperature is sepsis? ›
An affected person is considered to have sepsis if they meet two or more of the SIRS criteria, which are: Fever of 38 C / 100.4 F or more. Hypothermia of 36 C / 96.8 F or less. A pulse of more than 90 beats a minute.What are the warning signs of sepsis? ›
- confusion or disorientation,
- shortness of breath,
- high heart rate,
- fever, or shivering, or feeling very cold,
- extreme pain or discomfort, and.
- clammy or sweaty skin.
- Turn on the digital thermometer. ...
- Hold the thermometer tightly in place until you hear the thermometer beep indicating it's done.
Fever is a sign that the body is combating an infection. It helps kill bacteria and viruses. It also boosts production of infection-fighting white blood cells. There's generally no need to worry about bringing a fever down unless it's causing your child discomfort.
Can you get a low-grade fever with a cold? ›
The common cold is very easily spread to others. It's often spread through airborne droplets that are coughed or sneezed into the air by the sick person. The droplets are then inhaled by another person. Symptoms may include a stuffy, runny nose, scratchy, tickly throat, sneezing, watery eyes and a low-grade fever.Does low-grade fever work with Covid? ›
Fever seems to be one of the more common early markers of COVID-19, Kline noted. But you shouldn't necessarily expect a high-grade fever with dangerously elevated temperatures. Many people with the disease run a low-grade fever for days, she said, and some may have no fever at all.Why do I run a low-grade fever everyday? ›
A persistent low grade fever is a sign of an underlying issue, such as a mild infection or chronic condition. The fever may persist while the person is fighting off the infection. For the most part, persistent low grade fevers are not a cause for concern.Can you have a temperature with allergies? ›
Can Allergies Cause Fever? According to the American College of Allergy, Asthma, and Immunology, allergies do not cause a fever. However, an allergic reaction can trigger a sinus infection, eventually leading to a fever.Why do I have a low-grade fever but not sick? ›
A low-grade fever may develop following immunizations, in the course of teething or a symptom of any inflammatory or autoimmune condition and can also develop as a side effect of certain medications. Low-grade fever may not need any treatment if there are no symptoms.When does COVID fever start? ›
Symptoms may appear 2-14 days after exposure to the virus. Anyone can have mild to severe symptoms. Possible symptoms include: Fever or chills.Can you have no fever for 3 days with COVID? ›
Although a fever is a common symptom of this virus, it's still possible to have COVID-19 without a fever, especially within the first few days after being infected. In fact, one study found that just 55.5% of the surveyed COVID-19 patients reported experiencing a fever.How long can a low grade fever last? ›
Most low-grade fevers go away without medical intervention after 1 to 3 days, but a persistent or chronic fever may last or keep coming back for more than 10 days.How do I know I have Covid and not allergies? ›
A runny or stuffy nose, cough, tiredness, even shortness of breath and a lack of smell/taste can occur in both allergies and COVID-19. But a cough from COVID-19 is typically dry, whereas in allergies, a cough is wet and usually more sneeze-like. A stuffy nose from allergies can cause loss of taste/smell.Can you get a fever from stress? ›
Both acute and chronic stress can trigger fever-like symptoms, including an elevated body temperature, body chills or aches, fatigue, and flushed skin. Psychogenic fevers are rare, but they are most common in females.
Can you have a fever with no other symptoms? ›
Colds, flu and other viral infections are the most common cause. Fever may be the only symptom for the first 24 hours. The start of viral symptoms (runny nose, cough, loose stools) is often delayed.