Fever: Causes, Symptoms, and Treatment
Medically reviewed by Sumiran Racherla, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Fever?
A primary care doctor, such as a family medicine or internal medicine doctor, usually treats a fever. A pediatrician, a doctor for babies and children, sees children. An infectious disease doctor, who treats infections, may help if the cause is hard to find. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is a fever?
A fever is a body temperature that is higher than normal. A normal temperature differs from person to person, but it is usually around 98.6°F (37°C). A fever is not a disease. It is usually a sign that your body is trying to fight an illness or infection.
A child has a fever at or above 100.4°F (38°C) measured in the bottom. For a child, 99.5°F (37.5°C) in the mouth or 99°F (37.2°C) under the arm also counts as a fever. An adult probably has a fever when the mouth temperature is above 99°F to 99.5°F (37.2°C to 37.5°C), depending on the time of day.
Symptoms
A fever is itself a rise in body temperature. Some children have febrile seizures, which are seizures brought on by a fever.
Causes and who gets it
Infections cause most fevers. Your body raises its temperature to try to kill the virus or bacteria that caused the infection. Almost any infection can cause a fever. Examples are colds, flu-like illnesses, sore throats, ear infections, sinus infections, bronchitis, and pneumonia. Urinary tract infections, skin infections, appendicitis, meningitis, and stomach or bowel infections can also cause a fever.
Other causes include medicines, heat illness, cancers, and autoimmune diseases. The first symptom of a cancer may be a fever, especially with Hodgkin disease, non-Hodgkin lymphoma, and leukemia.
How doctors diagnose it
Your provider will do a physical exam. Tests may include blood tests, a urine test, and a chest x-ray.
Treatment
Treatment depends on the cause of the fever. If the fever is mild and you have no other problems, you do not need treatment. Drink fluids and rest. Lower a fever if you or your child is uncomfortable, vomiting, dried out, or not sleeping well. The goal is to lower the fever, not to remove it completely.
These steps can help:
- A lukewarm bath or sponge bath may help cool someone with a fever. This is effective after medicine is given, otherwise the temperature might bounce right back up.
- Do not use cold baths, ice, or alcohol rubs, because they often cause shivering, which raises the core body temperature.
- Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) help reduce fever in children and adults.
- Follow the package instructions and know how much you or your child weighs.
- Do not give aspirin to a child unless the child's provider tells you to.
- Do not give ibuprofen to children 6 months or younger.
- For a child 3 months or younger, call the child's provider before giving any medicine.
When to see a doctor
Call your child's provider right away if your child:
- is 3 months or younger and has a rectal temperature of 100.4°F (38°C) or higher.
- is 3 to 12 months old and has a fever of 102.2°F (39°C) or higher.
- is 2 years or younger and has a fever that lasts longer than 24 to 48 hours.
- has a fever of 105°F (40.5°C) or higher, unless it comes down readily with treatment and the child is comfortable.
Call your own provider right away if you are an adult and you:
- have a fever that stays at or keeps rising above 103°F (39.4°C).
- have a serious medical illness, such as a heart problem, sickle cell anemia, diabetes, cystic fibrosis, or COPD.
- have a weakened immune system, a new rash or bruises, or pain with urination.
Call 911 or the local emergency number if you or your child has a fever and:
- cannot be awakened easily or at all.
- seems confused.
- cannot walk.
- has difficulty breathing, even after the nose is cleared.
- has blue lips, tongue, or nails.
- has a very bad headache or a stiff neck.
- has a seizure.
- is a child who cries and cannot be calmed.
- is a child who refuses to move an arm or leg.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Either type of doctor can check a fever, look for its cause, and order simple tests such as blood or urine tests. They can also follow up if fevers keep coming back and tell you when you need an urgent visit or the emergency room.
Common questions
Is a fever dangerous?
Not always. A simple cold or other viral infection can sometimes cause a high fever, and this does not mean you or your child has a serious problem.
Can a fever cause a seizure?
Yes, some children have a febrile seizure when they have a fever. Most are over quickly, do not mean the child has epilepsy, and do not cause permanent harm. If your child has a seizure with a fever, call 911 or the local emergency number.
When should I call about a baby's fever?
Call the baby's provider right away if your baby is 3 months or younger and has a rectal temperature of 100.4°F (38°C) or higher. Also call the provider or go to the emergency room if your baby does not make tears when crying or has not urinated in the past 8 hours.
Sources
- MedlinePlus - Fever
- MedlinePlus - Fever (Medical Encyclopedia)
- MedlinePlus - When your baby or infant has a fever
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
