Fever in children: when to worry

Clinical practice · October 2026 · 4 minute read

A high temperature in a child is 38°C or more. Most fevers are caused by common infections and get better on their own, and the number on the thermometer matters less than how your child looks and behaves. Get urgent advice from NHS 111 or your GP if your baby is under 3 months with a temperature of 38°C or more, or 3 to 6 months with 39°C or more. Call 999 straight away if your child shows any of the red flags below.

Call 999 if your child

• has a rash that doesn't fade when you press on it, or any rash that is spreading quickly;
• has a stiff neck, or is bothered by light;
• has a fit for the first time, or can't stop shaking;
• has unusually cold hands and feet, or blue, grey, pale or blotchy skin, lips or tongue;
• is drowsy and hard to wake;
• is extremely agitated, won't stop crying or is confused;
• has difficulty breathing, is breathless or breathing very fast;
• isn't responding as usual, or isn't interested in feeding or their normal activities.

Trust your instinct. If your child seems seriously unwell to you, call 999.

Get urgent advice from NHS 111 or your GP if your child

• is under 3 months and has a temperature of 38°C or more, or you think they have a high temperature;
• is 3 to 6 months and has a temperature of 39°C or more, or you think they have a high temperature;
• has other signs of illness, such as a rash;
• has had a high temperature for 5 days or more;
• won't eat, or isn't their usual self, and you're worried;
• seems dehydrated: fewer wet nappies, sunken eyes, or no tears when crying.

Also get advice if you're worried, or if paracetamol or ibuprofen isn't helping.

Looking after your child at home

Do:

• give plenty of fluids, and keep breastfeeding if your baby is breastfed;
• offer food if they want it;
• watch for signs of dehydration;
• check on them regularly, including during the night;
• keep them off school or nursery while they have a high temperature;
• give paracetamol or ibuprofen if they seem distressed or uncomfortable, checking the packet for the right dose for their age.

Don't:

• undress them or sponge them down to cool them. A high temperature is the body's natural response to infection;
• cover them in lots of clothes or bedding;
• give aspirin to anyone under 16;
• give paracetamol and ibuprofen at the same time, or alternate them, unless a health professional tells you to;
• give paracetamol to a baby under 2 months;
• give ibuprofen to a baby under 3 months or under 5kg, to a child with chickenpox or who is dehydrated, or to a child with asthma unless a doctor has said it's safe.

Taking a temperature

Use a digital thermometer. Under the arm is best for babies and young children. Write down the readings and the times, along with any medicines given. It helps whoever you speak to next.

A note on babies

A fever in a baby under 3 months always needs to be checked the same day, even if they otherwise seem well. Some vaccinations can cause a mild fever, but don't assume that's the cause without advice.

Where Eviqa Health fits

Eviqa Health members can message, call or video our registered clinicians when a child is unwell, to talk through what you're seeing and where to go next. We follow up the next day. Babies under three months with a fever are always directed to face-to-face care, and in an emergency, always call 999.

Sources

• NHS: Fever in children (opens in a new tab)
• NICE NG143: Fever in under 5s, traffic light table (opens in a new tab)

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