You or someone you love has a fever — here is what to know
A fever can feel scary. Your body is hot, you feel worn out, and your mind starts racing. But most of the time, a fever is actually your body doing its job. It is a sign that your immune system — the part of your body that fights illness — has kicked into gear.
This guide will help you understand what a fever means, how to stay comfortable, and most importantly, when it is time to call a doctor or head to the emergency room.
What is a fever, exactly?
Normal body temperature is usually around 98.6°F (37°C), but it can shift a little throughout the day. It tends to be lower in the morning and slightly higher in the evening. Most doctors define a fever as a temperature of 100.4°F (38°C) or higher.
A fever is not a sickness itself. It is a symptom — a sign that something else is going on inside the body. Most often, that something is an infection caused by a virus or bacteria. The rise in temperature actually makes it harder for germs to survive and helps your immune system work faster.
A high number on the thermometer does not always mean a serious problem. How the person acts and feels matters just as much as the number. A child with a 103°F fever who is alert, drinking fluids, and playing is generally less worrying than a child with a 101°F fever who is very hard to wake up.
Common causes of fever
Viruses are the most common cause of fever. The flu, colds, COVID-19, and many stomach bugs can all bring on a fever. These usually get better on their own within a few days as your body fights off the virus.
Bacterial infections — infections caused by bacteria — can also cause fever. Examples include strep throat, urinary tract infections (UTIs), and ear infections. These sometimes need antibiotic medicine to clear up. Other causes include recent vaccinations, inflammatory conditions (when the body’s immune system becomes overactive), and sometimes certain medicines.
In rare cases, a fever can point to something more serious. That is why it helps to pay attention to other symptoms alongside the fever — like a rash, stiff neck, trouble breathing, or severe pain.
How to take care of yourself or your child at home
Rest is one of the most helpful things you can do. Your body is using a lot of energy to fight off whatever is making you sick. Drinking plenty of fluids — water, broth, or diluted juice — is also very important. Fever makes you lose water faster than usual, and staying hydrated (keeping enough fluid in your body) helps you recover.
Over-the-counter medicines like acetaminophen or ibuprofen can lower a fever and ease discomfort. Always follow the dosing directions on the package, and use a product made for children when treating a young child. Never give aspirin to anyone under 18 unless a doctor has specifically told you to — it can cause a rare but serious condition called Reye’s syndrome.
Dress lightly and keep the room comfortably cool. A lukewarm sponge bath can also help bring the temperature down gently. Avoid cold baths or ice — these can cause shivering, which actually raises the body’s core temperature.
Fever in babies and young children
Age matters a great deal when it comes to fever. Babies under 3 months old with any fever of 100.4°F (38°C) or higher should be seen by a doctor right away, even if they seem fine. Their immune systems are still very new, and infections can become serious very quickly in newborns.
Babies between 3 and 6 months old with a fever should also be evaluated promptly. For children older than 6 months, the height of the fever and how the child looks and behaves helps guide what to do next.
Some children between the ages of 6 months and 5 years have what are called febrile seizures (fe-BRILE SEE-zherz) — brief seizures triggered by a rapidly rising fever. These are frightening to watch but are usually not harmful on their own. Still, any seizure in a child should be reported to a doctor right away.
When to get help
Some situations mean you should call a clinician or go to an emergency room without waiting. Trust your instincts — if something feels seriously wrong, it is always okay to seek care.
- Any fever in a baby under 3 months old. Do not wait and see. Call a doctor or go to the ER right away.
- A fever above 104°F (40°C) that does not come down with medicine, or that keeps returning.
- A fever lasting more than 3 days in a child, or more than 5 days in an adult.
- Stiff neck, severe headache, or sensitivity to light. These can be signs of meningitis (men-in-JY-tis), an infection around the brain and spinal cord.
- A rash that appears alongside a fever, especially one that looks like small red or purple spots that do not fade when you press on them.
- Trouble breathing, chest pain, or blue lips. Call emergency services immediately.
- Confusion, extreme drowsiness, or difficulty waking up. This applies to both children and adults.
- Signs of dehydration such as no wet diapers for 8 hours in a baby, no urination for many hours in an adult, very dry mouth, sunken eyes, or no tears when crying.
- A fever in someone with a weakened immune system, such as a person going through chemotherapy, someone with HIV, or a transplant recipient. These individuals need medical attention sooner.
A note about checking your results
If you have had blood work or other tests done while you have a fever, some of the numbers may look unusual. That is often a normal response to infection. The Umuchi app can help you understand what those lab result terms mean in plain language, so you feel less confused while you wait to speak with your doctor.
You are doing the right thing by paying attention
Fever can feel alarming, but most fevers in otherwise healthy people get better within a few days with rest, fluids, and a little patience. Knowing the warning signs — and acting on them — is the most important thing you can do.
Be gentle with yourself or your child during recovery. The body is working hard. Most of the time, that hard work pays off, and things start to improve sooner than expected. When something does not feel right, reaching out to a healthcare provider is always the right call.
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