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What temperature is a fever in children?
Guidelines define fever differently. NHS says 38°C or more. MedlinePlus gives general adult context. Check your child's symptoms, not just the number.
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What the guidelines say
| Organisation | What it says | Source |
|---|---|---|
| NHS | A high temperature in babies and children is 38°C or more. Use a digital thermometer in the armpit. A fever is common and usually returns to normal within 1 to 4 days. | [2] |
| MedlinePlus | A fever is a body temperature higher than normal. Normal is usually around 98.6°F (37°C). This source focuses on adults and general causes, not a specific child fever threshold. | [1] |
Where they agree
Both sources agree that a fever is a sign of illness, not a disease itself. They both state that fever is the body’s natural response to fighting an infection. MedlinePlus says most bacteria and viruses do poorly at higher body temperatures, and fever activates the immune system [1]. NHS similarly describes a high temperature as the body’s natural and healthy response to infection [3]. Both also agree on the importance of fluids to prevent dehydration [1][3]. Neither recommends aspirin for children. MedlinePlus says children with fevers should not take aspirin [1]. NHS says do not give aspirin to children under 16 [3].
Where they differ (and why it may not matter)
The main difference is the threshold. NHS gives a clear number for children: 38°C or more is a high temperature [2]. MedlinePlus does not give a specific child threshold. It mentions a normal adult temperature around 98.6°F (37°C) but does not define a fever number for children [1]. This difference likely reflects that each source serves a different audience. NHS is a UK guide specifically for parents of children. MedlinePlus is a general US health resource covering fever across ages. For practical purposes, the NHS number is the one to use for a child. The exact threshold matters less than how your child looks and behaves. NHS stresses that a child with a fever might feel hot, look unwell, or have a febrile seizure [2]. It also lists many warning signs that require medical help, regardless of the exact temperature [3].
Another difference involves medicine. NHS gives detailed rules: no paracetamol under 2 months, no ibuprofen under 3 months or under 5kg, and no alternating ibuprofen and paracetamol unless told by a professional [3]. MedlinePlus only says a provider may recommend acetaminophen or ibuprofen for a very high fever [1]. This difference is practical, not contradictory. NHS provides more specific safety guidance for young children. MedlinePlus gives a general statement for all ages.
When to see a doctor or go to the emergency department
Call your doctor or a health advice line if your child is under 3 months old with a temperature of 38°C or higher, or if you think they have a high temperature. Also call if your child is 3 to 6 months old with a temperature of 39°C or higher. Call if the fever lasts 5 days or more, if your child has a rash, is dehydrated, or is not their usual self [3].
Go to the emergency department (call your emergency number in the UK) if your child has a stiff neck, a rash that does not fade when pressed with a glass, is bothered by light, has a first febrile seizure, has cold hands and feet, has blue or pale skin or lips, is drowsy and hard to wake, is extremely agitated or confused, has difficulty breathing, or is not responding normally [3].
Sources
[1] MedlinePlus — “Fever” (2025), section “Introducción”, p. 1 — https://medlineplus.gov/fever.html [2] NHS — “High temperature (fever) in children” (2025), section “High temperature (fever) in children”, p. 1 — https://www.nhs.uk/conditions/fever-in-children/ [3] NHS — “High temperature (fever) in children” (2025), section “Don’t”, p. 1 — https://www.nhs.uk/conditions/fever-in-children/
This guide summarises published paediatric guidelines. It is not medical advice and does not replace your paediatrician. In an emergency, call your local emergency number.
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