When a fever in adults needs a doctor

What a fever is

A fever is your body's normal response to infection or inflammation. In adults, anything from 38°C (100.4°F) and up qualifies. Most fevers are caused by viral infections that pass within a few days. A fever itself is rarely the danger — what matters is the cause and how the rest of you is doing.

Signs you can manage at home

For an otherwise healthy adult, a short fever with mild symptoms usually doesn't need a clinic visit. Rest, drink fluids, and treat discomfort with paracetamol or ibuprofen if you can take them. Check in on your symptoms twice a day.

Reasons to call a doctor

• Fever lasts more than three days, or returns after going away.
• Temperature stays above 39.5°C (103°F) despite medication.
• New severe headache, neck stiffness, or sensitivity to light.
• Confusion, drowsiness that's hard to shake, or trouble staying awake.
• Difficulty breathing or chest pain.
• A rash that spreads quickly or doesn't fade when pressed.
• Painful urination, severe abdominal pain, or persistent vomiting.

When to go straight to the hospital

Some combinations should bypass the clinic and head to emergency care: a stiff neck with a severe headache, confusion or seizures, breathing that feels labored, a rash with very high fever, or fever in someone who is pregnant, has a weakened immune system, or has recently had surgery.

A note on measuring

Oral or armpit thermometers are fine for adults. Avoid a hot drink or shower in the half hour before measuring — both can throw the reading off by half a degree. If you're tracking a fever over time, write down the time and the number; trends matter more than any single reading.

Bottom line

Most fevers in adults get better on their own. Pay attention to what your body is telling you alongside the temperature. When in doubt, especially with the warning signs above, don't wait it out — call.