Fever

Key takeaways

• A fever is when your body temperature is higher than normal. This is typically anything over 100.4°F (37.8°C).
• In many cases, a fever is not something to worry about. A fever is a natural sign that your body is fighting an infection.
• Fevers are temporary and often do not require any medical treatment.
• A lukewarm bath or fever-reducing medicine may help you feel more comfortable.

Overview

What is a fever?

A fever occurs when your body temperature is temporarily higher than normal. Normal body temperature can vary person-to-person and at different times of the day. Typically, the average body temperature is 98.6°F (37°C). Anything higher than 100.4°F (37.8°C) is considered a fever.

A fever is not an illness itself but a response from your immune system when something inside your body isn't right. For most adults and children, fever symptoms are temporary and mildly uncomfortable. For infants, a fever may be a sign of a serious infection.

Other names for fever:

Pyrexia (abnormally high body temperature), hyperpyrexia (high fever)

Types of fevers:

Your body temperature determines the type of fever you have:

• Low-grade fever: Body temperature rises to 100.5°F (38°C)
• Moderate fever: Body temperature is between 102.2°F - 104°F (39.1°C - 40°C)
• High-grade fever: Body temperature is 104°F (39.4° C) or above

What are the symptoms of a fever?

Most health care providers consider a fever to be 100.5°F (38°C) or higher for adults and children. Along with a high temperature, you may also notice these symptoms:

• Flushed face
• Hot, dry skin
• Sweating
• Chills and shivering
• Headache
• Muscle aches
• Loss of appetite
• Irritability
• Dehydration
• General weakness
• Nausea

It is especially important to keep an eye out for these symptoms when caring for babies, young children, and disabled people - anyone who may not be able to express how they feel.

How is a fever diagnosed?

The best way to diagnose a fever is to take a temperature using a thermometer. There are a few different types of thermometers that can measure temperature from different parts of the body. Some of the most common thermometers are:

• Digital thermometer — Temperature can be taken orally, rectally, or under the armpit.
• Tympanic thermometer — Temperature taken from your ear (not recommended in babies younger than 6 months of age).
• Temporal artery — Temperature taken across the forehead area.

The following temperatures or higher indicate a fever:

• Infants (babies under 1 year old) — 99°F (37.2°C) (oral & armpit) or 100.5°F (38°C) (rectal)
• Adults and children (older than 1 year old) — 100.5°F (38°C) (oral)

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Possible Causes

What can cause a fever?

Fevers are usually caused by an infection or illness. They can also be a reaction to a vaccine. On rare occasions, you can also get a fever from overheating or being in the sun for too long.

Some common illnesses and infections that may cause a fever:

• Chicken pox
• COVID-19
• Coughs & Bronchitis
• Ear infections & earaches
• Influenza (the flu)
• Mononucleosis
• Shingles
• Sinus infections & congestion
• Strep throat
• Upper respiratory infections
• Urinary tract and bladder infection
• Zika virus

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Treatment & management

How is a fever treated?

Fevers are temporary and often do not require any medical treatment. There are some things you can do at home to help lower a fever, especially if you're feeling uncomfortable.

• Take a lukewarm bath or sponge bath
• Stay hydrated by drinking plenty of fluids, water, ice pops, soup, etc.
• Get plenty of rest
• Take antibiotics prescribed by your provider to treat any bacterial infection that is causing the fever. Unfortunately, antibiotics cannot help with viral infections.
• Take fever-reducing medicine. Medications such as ibuprofen and acetaminophen can help relieve muscle aches and help lower your temperature.

If you're experiencing other symptoms along with a fever, it's important to work with a health care provider to determine the cause and get the appropriate treatment. MinuteClinic offers a variety of services that can help with diagnosis and treatment. 

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When to seek medical care

Go to the hospital or call 911:

For newborns and infants younger than 3 months old:

• If baby's temperature is above 100.4°F (38°C)
• If baby's fever is accompanied by any of these symptoms:
• Difficulty waking up to be fed
• Difficulty breathing
• Vomiting
• Inconsolable or non-stop crying

For children and adults:

• If temperature is above 102°F (38.9°C) for two or more days
• If fever is accompanied by any of these symptoms:
• Severe abdominal pain
• Difficulty breathing or swallowing
• Pain when urinating
• Rash
• Stiff neck
• Difficulty waking up
• Mental confusion, strange behavior or altered speech
• Unusual sensitivity to bright light
• Persistent vomiting
• Convulsions or seizures

Call your or your child's provider

For infants and children, call a health care provider if they:

• Are younger than 3 months old and have a temperature above 100.4°F (38°C)
• Are older than 3 months old and have a temperature higher than 102°F (38.9°C) that lasts longer than two days
• Their fever is accompanied by these symptoms:
• Sluggishness (lacking energy), confusion or having poor eye contact with you
• Rash
• Ear pain, or pulling at their ear
• Unusually irritable
• A runny nose, sore throat, diarrhea, stomachache, or other symptoms causing a lot of discomfort

For adults, call a health care provider if:

• You are pregnant and have a temperature of 101°F (38.3°C) or higher
• Your temperature is 103°F (39.4°C) or higher
• You have a runny nose, sore throat, diarrhea, stomachache, or other symptoms causing a lot of discomfort

In general, if you are concerned about your fever, check in with a health care provider. You can find many services at a MinuteClinic location near you.

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This material is for reference only and should not be used to determine treatment for specific medical conditions.

Please visit a healthcare provider for evaluation, diagnosis, and treatment of any symptoms you may be experiencing. If you're experiencing a medical emergency, please dial 911 or visit your local Emergency Department.

References used as sources for this page

1. Fever | John Hopkins Medicine. Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/fever. (Accessed September 21, 2022)
2. Fever: MedlinePlus Medical Encyclopedia. Available at: https://medlineplus.gov/ency/article/003090.htm. (Accessed September 21, 2022)
3. Fever Symptoms: In Adults, in Children, in Babies, Treatment, and More. Available at: https://www.healthline.com/health/fever-symptoms#treatment. (Accessed September 21, 2022)

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