Conditions
Fever in adults: home care and when to see a doctor
What counts as a fever in adults, common causes, how to look after yourself at home, and the warning signs that mean you should seek medical or emergency care.
Key takeaways
- In adults, a temperature of 38°C (100.4°F) or higher is a fever.
- Most fevers are caused by viral infections and settle within a few days.
- Seek care for a fever of 39.4°C (103°F) or higher, one lasting more than three days, or any warning signs.
Fever is a rise in body temperature, usually as part of the body’s response to infection. It is uncomfortable, but it is not usually dangerous in healthy adults.
What counts as a fever?
Normal body temperature varies between people and through the day, but is typically around 36.1–37.2°C (97–99°F). A temperature of 38°C (100.4°F) or higher is a fever. Convert readings and check what they mean with our fever and temperature tool.
Common causes
- Viral infections such as colds, flu and COVID-19
- Bacterial infections, for example of the urinary tract, chest, skin or ear
- Inflammatory conditions
- Reactions to some medicines or vaccines
- Heat-related illness
Looking after yourself at home
- Rest, and drink plenty of fluids — enough that your urine stays pale.
- Wear light clothing and keep the room comfortably cool.
- Paracetamol (acetaminophen) or ibuprofen can make you more comfortable. Follow the label and do not double up on products containing the same medicine.
- You do not need to bring a fever down if you feel all right — treat the discomfort, not the number.
When to contact a doctor
- Your temperature is 39.4°C (103°F) or higher
- The fever lasts more than three days
- You have a weakened immune system, for example from chemotherapy, or you are pregnant
- You have recently travelled abroad, especially to an area where malaria is present
- You have a long-term condition such as heart, lung or kidney disease
- You feel worse rather than better, or you are worried
Call your emergency number or go to the emergency department for fever with: a stiff neck or severe headache; a rash that does not fade when you press a glass against it; confusion or unusual drowsiness; difficulty breathing or chest pain; a seizure; persistent vomiting; or pain when passing urine with back pain and shivering.
Fever in children
Children need different thresholds. A baby under 3 months with a temperature of 38°C (100.4°F) or higher needs urgent medical advice. See the care navigator and choose “It’s for a child”.
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