Fever
Also known as: Fever of other or unknown origin
General information only. Anpheros does not diagnose and does not recommend treatment. Talk to a doctor or pharmacist about your situation. In an emergency, call 112 (or your local emergency number).
In short
A fever is a body temperature that is higher than normal, which is usually around 98.6 °F (37 °C). It is not a disease, but rather a sign that the body is trying to fight an illness or infection, as most bacteria and viruses struggle to survive at higher temperatures. Fevers can also be caused by medicines, heat illness, cancers, autoimmune diseases, and some childhood vaccines. Treatment depends on the cause, and may include drinking enough liquids to prevent dehydration or taking over-the-counter medicines like acetaminophen or ibuprofen.
Source: MedlinePlus, National Library of Medicine.
AI-generated summary of the sources cited on this page, checked automatically against them. Not reviewed by a clinician; not medical advice.
Codes
Description
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.
Next to it in ICD-10
- R49.0Hoarse or strained voice (dysphonia)
- R49.1Loss of voice (aphonia)
- R49.2Too much or too little nasal sound in the voice
- R50.2Fever caused by a medicine
- R51Headache
- R52Pain
Neighbouring codes in the classification, not a medical link.
What people report
Not enough data yet. Anonymous counts appear here only for groups of at least 20 people who agreed to share them.
External resources
Questions
What is the ICD-10 code for Fever?
R50 (WHO, International Classification of Diseases, 10th Revision).
What is the ICD-11 code for Fever?
MG26: Fever of other or unknown origin (WHO, ICD-11 for Mortality and Morbidity Statistics).
Sources and attribution
- Source: MedlinePlus, National Library of Medicine.
- ICD-10 codes and titles © World Health Organization. Source: WHO, International Classification of Diseases, 10th Revision (2019).
- ICD-11 for Mortality and Morbidity Statistics, © World Health Organization, licensed under CC BY-ND 3.0 IGO.
- Names other than the official source titles: Anpheros translations and plain-language names, made with AI assistance and checked automatically; the source names are in English.
Anpheros Search catalog 2026.10.5, published 17 October 2026. About the data →
About this page. This page brings together public information from official sources, each cited where it is used. It is not medical advice, it is not a diagnosis, and it does not tell you which treatment to take.
Treatments. Indications are quoted unchanged from official product information (European Medicines Agency, U.S. Food and Drug Administration). They describe what a medicine is approved for, not whether it is right for you. Approved uses can differ between countries. Always read the package leaflet and follow your doctor's or pharmacist's advice.
What people report. Figures marked "reported by Anpheros users" are anonymous counts from at least 20 people who agreed to share them. They show what people report, not what works, and they are not clinical evidence.
Links between terms. "May be associated with" means the link appears in a cited source. It does not mean you have that condition.
In an emergency, call 112 (or your local emergency number). Do not delay seeking medical help because of something you read here.