Fever

Summary

A fever is a body temperature that is higher than normal. A normal temperature can vary 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.

Infections cause most fevers. You get a fever because your body is trying to kill the virus or bacteria that caused the infection. Most of those bacteria and viruses do well when your body is at your normal temperature. But if you have a fever, it is harder for them to survive. Fever also activates your body’s immune system.

Other causes of fevers include:

• Medicines, including some antibiotics, blood pressure medicines, and anti-seizure medicines
• Heat illness
• Cancers
• Autoimmune diseases
• Some childhood vaccines

Treatment depends on the cause of your fever. If the fever is very high, your health care provider may recommend taking an over-the-counter medicine such as acetaminophen or ibuprofen. Adults can also take aspirin, but children with fevers should not take aspirin. It is also important to drink enough liquids, to prevent dehydration.

National Institute of Allergy and Infectious Diseases

Children

• An Acetaminophen Overdose Is Serious and It Can Happen Easier Than You Might Think Mayo Foundation for Medical Education and Research
• Febrile Seizures National Institute of Neurological Disorders and Stroke
• Getting the Most From a Doctor’s Visit (For Patents) Nemours Foundation
• How to Take a Rectal Temperature Nemours Foundation
• How to Take an Axillary Temperature Nemours Foundation
• How to Take an Oral Temperature Nemours Foundation
• Kid’s Guide to Fever Nemours Foundation

Clinical Trials

• ClinicalTrials.gov: Fever National Institutes of Health

Specifics

• Cryopyrin-Associated Autoinflammatory Syndromes (CAPS) American College of Rheumatology
• Familial Mediterranean Fever Mayo Foundation for Medical Education and Research
• Periodic Fever, Aphthous Stomatitis, Pharyngitis, Adenitis Syndrome (PFAPA) (Juvenile) American College of Rheumatology

Genetics

• Familial cold autoinflammatory syndrome: MedlinePlus Genetics National Library of Medicine
• Familial Mediterranean fever: MedlinePlus Genetics National Library of Medicine
• Mevalonate kinase deficiency: MedlinePlus Genetics National Library of Medicine
• Muckle-Wells syndrome: MedlinePlus Genetics National Library of Medicine
• Nakajo-Nishimura syndrome: MedlinePlus Genetics National Library of Medicine
• Neonatal onset multisystem inflammatory disease: MedlinePlus Genetics National Library of Medicine
• Tumor necrosis factor receptor-associated periodic syndrome: MedlinePlus Genetics National Library of Medicine
• Yao syndrome: MedlinePlus Genetics National Library of Medicine

Patient Handouts

• Familial Mediterranean fever Medical Encyclopedia
• Fever Medical Encyclopedia
• When your baby or infant has a fever Medical Encyclopedia

Start Here

• Fever Mayo Foundation for Medical Education and Research
• Fever (High Temperature) In Kids Nemours Foundation

Diagnosis and Tests

• Fever American Academy of Family Physicians
• Fever in Infants and Children American Academy of Family Physicians

Treatments and Therapies

• Fever Treatment: Quick Guide to Treating a Fever Mayo Foundation for Medical Education and Research
• Fever: First Aid Mayo Foundation for Medical Education and Research
• Thermometers: Understand the Options Mayo Foundation for Medical Education and Research

Related Issues

• Hot Flashes and Night Sweats National Cancer Institute

Women

• Hyperthermia and Pregnancy Organization of Teratology Information Specialists

Find an Expert

• National Institute of Allergy and Infectious Diseases National Institute of Allergy and Infectious Diseases

Journal Articles

• Fever

Encyclopedia

• Temperature measurement Medical Encyclopedia