PRACTICAL HEALTH · SYMPTOMS
🌡️ Fever
Fever is a temporary rise in body temperature and is often part of the body's response to an infection. Age and accompanying symptoms matter.
What should you notice?
- The measured temperature and how it was taken.
- How long the fever has lasted.
- Breathing difficulty, severe headache, rash or stiff neck.
- Hydration and urine output.
- Age, pregnancy, immune status and important medical conditions.
Possible causes
These are examples, not a diagnosis. The same symptom can have many different causes.
- Viral infections.
- Bacterial infections.
- Some inflammatory conditions.
- Heat-related illness.
- Certain medicines or other medical causes.
What can you do initially?
- Drink adequate fluids when appropriate.
- Rest and monitor symptoms.
- Do not use antibiotics unless prescribed for a bacterial infection.
- Seek medical advice when fever is persistent, concerning or accompanied by significant symptoms.
🚨 Warning signs
- Difficulty breathing, confusion or seizure.
- Severe headache with stiff neck.
- Signs of severe dehydration.
- A concerning widespread rash with significant illness.
- Important: an infant younger than 3 months with a temperature of 100.4°F (38°C) or higher needs prompt medical assessment.
If you believe the situation is life-threatening, call 911 in the United States.
Medical sources
Medical review: September 2026.
Educational information: This page provides general health information. It does not establish a diagnosis, prescribe treatment or replace evaluation by a qualified healthcare professional.