A fever is when your body temperature is higher than normal. The average body temperature is around 98.6°F (37°C).

Your average body temperature may be higher or lower than that. It can also fluctuate slightly throughout the day. These fluctuations can vary with age and how active you are. Your body temperature is typically highest in the afternoon.

When your body temperature rises higher than normal, it may be a sign that your body is in the process of fighting off an infection. It’s usually not a cause for alarm.

The following temperatures or higher indicate a fever:

  • Adults and children: 100.4°F (38°C) (oral)
  • Babies (under 1 year): 99°F (37.2°C) (armpit) or 100.4°F (38°C) (rectal)

Read on to learn more about what to expect with a fever, how and when to treat it, and when to seek help.

The general symptoms associated with a fever can include:

Febrile seizures in children

Children between 6 months and 5 years of age may develop febrile seizures. These seizures can occur during very high fevers. About one-third of children who have a febrile seizure will have another. Typically, children outgrow febrile seizures.

It can be very scary when your child has a febrile seizure. If this happens, you should do the following:

  • Place your child on their side.
  • Don’t place anything in your child’s mouth.
  • Seek medical attention if you suspect your child is having or had a febrile seizure.

Low-grade vs. high-grade fevers

A low-grade fever for adults and children is when your body temperature is elevated slightly above normal. This is generally between 98.8°F (37.1°C) and 100.3°F (38°C).

People with high-grade fevers should seek medical advice. For adults, this is an oral temperature of 103°F (39.4°C). For children over 3 months old, this is a rectal temperature of 102°F (38.9°F) or higher.

If your baby is under 3 months old and has a rectal temperature of 100.4°F (38°C) or higher, seek medical attention immediately.

When a fever breaks

When a fever breaks, your temperature will return to what’s normal for you, usually around 98.6°F (37°C). You may start to sweat or feel flushed as this is happening.

In adults and children

In cases of a mild or low-grade fever, it may not be a good idea to try to bring your temperature down too quickly. The presence of the fever could be helpful in fighting off an infection in your body.

In case of a high fever or a fever that’s causing discomfort, the following treatments may be recommended:

  • Over-the-counter (OTC) medications. Popular options include ibuprofen (Advil) or acetaminophen (Tylenol). They can help relieve your aches and pains and lower your temperature. Be sure to check dosing information for children.
  • Antibiotics. Your doctor will prescribe antibiotics if you have a bacterial infection that’s causing your fever. Antibiotics can’t be used to treat viral infections.
  • Sufficient fluid intake. A fever can lead to dehydration. Be sure to drink plenty of fluids, like water, juice, or broth. Rehydration solutions such as Pedialyte can be used for young children.
  • Keep cool. Wear lighter clothing, keep your environment cool, and sleep with light blankets. Taking a lukewarm bath may also help. The key is to keep cool, but not to induce shivering. This can make you feel worse.
  • Rest. You’ll need sufficient rest to recover from whatever is causing your fever. Avoid any strenuous activities that could elevate your body temperature.

Children and anyone under the age of 18 should never take aspirin for an illness. This is because of the risk of a rare, but fatal, condition called Reye’s syndrome.

In babies

If your baby has a rectal temperature of 100.4°F (38°C) or higher, seek medical attention immediately. Don’t give your baby OTC medications at home without first consulting their doctor for dosing and guidance.

A fever could be the only indication of a more serious condition. Your baby may need to receive intravenous (IV) medication and be monitored by a doctor until their condition improves.

In adults

Seek medical attention if you’re experiencing a fever with any of the following symptoms:

In children and babies

Seek medical attention for your child if they:

  • are younger than 3 months old and have a fever with a rectal temperature of 100.4°F (38°C) or higher
  • are over 3 months old and have a fever of 102°F (38.9°F) or higher
  • are over 3 months old and have had a fever for longer than 2 days

Also seek medical attention for your child if they have a fever and:

  • difficulty breathing
  • headache
  • skin rash
  • lack of energy or appear listless or lethargic
  • are inconsolable or crying continuously
  • stiff neck
  • appear confused
  • lack of appetite
  • aren’t consuming adequate fluids to produce wet diapers

A fever is when your body temperature is higher than normal. This is typically a sign that your body is in the process of fighting off some sort of infection. Fevers will typically go away within a few days.

Most low-grade and mild fevers are nothing to worry about. You should be able to relieve discomfort by taking OTC medications, staying hydrated, and getting plenty of rest.

Any fever in an infant younger than 3 months, or high grade-fevers in adults and children, should be assessed by a medical professional.