Fever in Adults: What It Means and When to Act

What is a fever?

A fever is a temporary rise in body temperature, usually a sign that your body is responding to an infection. It is one of the body's natural defences and, in most healthy adults, is not dangerous in itself. A normal body temperature is around 37°C, and a fever is generally considered a temperature of 38°C or above.

What causes a fever?

Most fevers in adults are caused by infections, and many of these are viral and self-limiting, such as colds and flu. Other causes include bacterial infections, heat exposure, certain medicines, and inflammatory conditions. Because many fevers are viral, antibiotics are often not the answer, since they treat bacteria, not viruses. You can read more in bacterial infections explained.

Common symptoms alongside a fever

• Feeling hot or shivery
• Sweating or chills
• Headache and aching muscles
• Tiredness and weakness
• A general feeling of being unwell

Looking after yourself at home

Many fevers settle on their own with simple self-care:

• Rest and avoid overexertion
• Drink plenty of fluids to stay hydrated
• Keep comfortable, not too hot or too cold
• Take paracetamol or ibuprofen if you are uncomfortable, following the leaflet
• Avoid wrapping up in heavy layers if you feel hot

There is no need to bring every fever down with medication; the aim is comfort rather than forcing the temperature to normal.

Do you need antibiotics?

A fever on its own does not mean you need antibiotics. Since many fevers are caused by viruses, antibiotics would make no difference and using them unnecessarily fuels antibiotic resistance explained. Where a doctor identifies a bacterial cause, they may prescribe an appropriate antibiotic; medicines such as those in our Amoxicillin guide and the broader antibiotics range are among the options used for confirmed bacterial infections. If you are prescribed a course, finish it as directed.

When to see a doctor

Contact a doctor or pharmacist for advice if:

• A fever lasts more than three days or keeps returning
• You have other symptoms that worry you
• You have a long-term health condition or a weakened immune system
• You feel increasingly unwell rather than better

When to seek urgent help

Get urgent medical care, or call emergency services, if you or someone else has a fever along with any of the following:

• A stiff neck and dislike of bright light
• A rash that does not fade when pressed with a glass
• Difficulty breathing or chest pain
• Confusion, drowsiness or difficulty waking
• A seizure (fit)
• Cold, clammy or mottled skin

These can be signs of a serious infection such as sepsis or meningitis and need immediate attention.

A note on temperature checks

Thermometers vary, so follow the instructions for your device. How you feel and your other symptoms are just as important as the exact number on the thermometer when deciding whether to seek help.

General information only — not medical advice. Always read the patient information leaflet and consult a doctor or pharmacist before starting any medication.