What is considered a fever? A simple guide for adults and children

A fever is often a sign that your body is doing what it’s supposed to do. In most cases, it means your immune system is working to fight off an infection.

But having a fever can leave you feeling uncomfortable and concerned. You may wonder how high is too high, what the numbers really mean and when it’s time to call a doctor.

Understanding what a fever is—and when it may signal something more serious—can help you take the right next step with confidence.

Let's take a closer look at what is considered a fever and when to seek care. 

What is considered a fever?

A fever is a temporary increase in body temperature, usually caused by an infection, illness or another medical condition.

Normal body temperature for adults averages around 98.6°F, but it can vary throughout the day. Many people naturally fall within a range of 98.6–99.9°F, which is not considered a true fever.

A fever is generally defined as:

• 100.4°F (38°C) or higher

Temperatures below this threshold may feel uncomfortable but are less likely to indicate illness on their own.

Parents, it’s easy to panic when your young child spikes a fever, but first, take a deep breath. Keep in mind that kids usually spike fevers faster than adults and the temperatures tend to be higher as well; this is because children have an immature immune system.

How to break a fever

Fortunately, for low-grade fevers, if you’re looking for how to break a fever, there are a few steps you can take to make yourself more comfortable at home.

Rest

Your body needs lots of rest to give your immune system a chance to recover. Keep your body cool by sleeping in light clothing.

Fluids

Fluids are essential since fevers can cause fluid loss and dehydration. For children younger than one year old, use oral rehydration products.

Over-the-counter medication

For adults, fever treatment often depends on both temperature and how you feel. If your temperature is below 102°F and discomfort is mild, over‑the‑counter medications such as acetaminophen, ibuprofen, naproxen or aspirin may help.

For children, medication should always be based on age and weight. Acetaminophen or ibuprofen may reduce discomfort, but doses must be followed carefully. It’s important to note that ibuprofen is not appropriate for children younger than 6 months of age (as their kidneys aren't yet fully developed), so acetaminophen is the only acceptable medication option.

If you have questions, contact your child’s pediatrician before giving medication.

When to worry about a fever

While most fevers are harmless and resolve on their own, certain situations can require medical attention. Age plays an important role in determining when you should seek care, as well as if you are experiencing any other symptoms.

Infants younger than 3 months old

If your child is less than 3 months old and has a fever, seek care immediately. For children older than 3 months, seek medical care if their fever reaches 102°F or higher.

Fever with any of the following symptoms can also be a cause for concern in children:

• Nonblanching dark rashes
• Extreme irritability or lethargy
• Severe pain
• Difficulty moving a part of the body, most importantly, the neck
• Trouble breathing or quick/forceful breathing
• Poor appetite or fluid intake with decreased urine output

Infants (3–6 months old)

For infants between 3 and 6 months old, contact your pediatrician if their fever reaches 101°F or higher. While not as urgent as newborn fevers, babies this age still require close monitoring due to their developing immune systems.

Infants (6–24 months old)

In most cases, if your baby is drinking plenty of fluids, sleeping well and still playing normally, it may not be too serious.

Call your pediatrician if:

• The fever is higher than 102°F
• The fever lasts longer than three days
• Symptoms such as cough, runny nose or diarrhea worsen

Children over 2 years

Fevers in children over 2 years old are common, and in most healthy kids, it is nothing to worry about. There are steps you can take at home to help lower it, such as fluids, rest and over-the-counter treatments. If your child’s fever reaches 102°F or higher, call their primary care provider or pediatrician.

Call your child’s provider if:

• The fever reaches 102°F or higher
• The fever lasts more than 72 hours
• Your child seems to be getting worse, even after the fever improves
• The fever does not respond to medication

Seek care right away if your child has a fever along with:

• Difficulty breathing or chest pain
• Confusion or unusual behavior
• Severe headache or abdominal pain
• Signs of dehydration
• A widespread rash or red or purple skin changes

Adults

If your fever reaches higher than 104°F, come in to see your doctor. Also see your doctor if you have additional symptoms such as:

• Seizures
• Loss of consciousness
• Stiff neck
• Trouble breathing
• Severe pain
• Swelling or inflammation in the body
• Pain with urination
• Any unusual vaginal discharge

When in doubt, reach out

If ever in doubt, please reach out to your primary care physician. We can help you evaluate your symptoms and guide you in the right direction so you or your child can get the care you need.

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