Short answer: A high temperature is 38 °C or more. A baby under 3 months with 38 °C or higher, or a baby aged 3 to 6 months with 39 °C or higher, needs urgent medical help. In older children, how your child seems matters more than the number: look at drinking, peeing, alertness and breathing. Give plenty of fluids and, if your child is uncomfortable, paracetamol or ibuprofen suitable for their age. Call your emergency number for red flags such as difficulty breathing, a rash that doesn't fade under pressure, a child who is hard to wake, or a seizure lasting more than five minutes.
The thermometer beeps: 38.4. And the question isn't “what do I give?” but “do I need to call someone?”
How to take your child's temperature
For babies and young children, the NHS recommends a digital thermometer under the armpit:
- Place the thermometer inside the top of the armpit.
- Gently close the arm over it and keep it pressed to the side of the body.
- Leave it for as long as the instructions say, then read it.
If your child has just had a bath or been wrapped up warmly, wait a few minutes and try again.
When a fever needs urgent help
- Under 3 months: 38 °C or higher — get urgent medical help, even if your baby otherwise seems well.
- 3 to 6 months: 39 °C or higher — get urgent medical help (unless they've had a vaccine in the past two days and seem otherwise well; ask if unsure).
- 3 months to 5 years: a temperature of 38 °C or higher lasting more than 5 days needs medical advice.
- Any age: a temperature below 36 °C, or feeling cold and shivery, can also be a sign of serious illness.
Look at your child, not just the thermometer. Drinking, peeing and responding to you tell you more than a number.
Call 999 (UK), 911 (US) or 112 (EU) if your child:
- has difficulty breathing — grunting, breathing very fast, or sucking in under the ribs;
- has blue, grey, pale or blotchy skin, lips or tongue;
- has a rash that doesn't fade when you press it (try pressing a glass against it);
- is floppy, hard to wake, or not responding as usual;
- has a weak, high-pitched or continuous cry;
- has skin that feels cold or clammy;
- hasn't peed for 12 hours;
- has a seizure for the first time, or one lasting more than 5 minutes.
Call NHS 111 (or your local equivalent) if you're worried and not sure what to do. Trust your instincts — you know your child best.
What to do at home
- Give plenty of fluids. If you're breastfeeding, keep feeding as normal.
- Look for signs of dehydration: dry mouth, no tears, sunken eyes, fewer wet nappies.
- Don't undress your child or sponge them down to cool them; a fever is a natural response to infection. Dress them normally and keep the room comfortable.
- Medicines: if your child is distressed or uncomfortable, give paracetamol or ibuprofen suitable for their age — not to chase a number, but for comfort. Paracetamol isn't for babies under 2 months, and ibuprofen isn't for babies under 3 months; check the packaging or ask a pharmacist. Don't alternate the two unless a health professional tells you to. Never give aspirin to under-16s.
- Check on your child regularly, including during the night.
- Keep them home from nursery or school while they have a fever.
Febrile seizures
Some young children — usually between 6 months and 6 years — have a seizure (fit) when they have a high temperature. It's frightening to see, but febrile seizures are unlikely to harm your child or cause long-term effects.
- Stay calm, note the time, and move anything nearby that could hurt them.
- Don't put anything in their mouth, and don't hold them down.
- After the seizure, place them in the recovery position.
- Call 999 (or your emergency number) if the seizure lasts more than 5 minutes, it's their first seizure, it affects only one side of the body, or they don't recover quickly.
Even if a seizure stops quickly, contact your GP or NHS 111 afterwards for advice.
Related reading
Month by month: The First Year (PDF, English) guides you through your baby's first twelve months.
Sources
- NHS — High temperature (fever) in children.
- NHS — When to get urgent medical help for babies and children under 5.
- NHS — Febrile seizures.
- NICE — Fever in under 5s: assessment and initial management (NG143).
Written by the Bloom Guides editorial team. Last updated: 20 October 2026. General information only — not a substitute for advice from your doctor, pharmacist or NHS 111.