Fever

Fever is the body deliberately raising its own temperature as part of an immune response. It is a sign that something is happening, not a disease in itself — and in most cases that something is an ordinary viral infection that will settle on its own.

A temperature of 38°C or above is generally considered a fever. But the number is a much poorer guide than most people expect. A child with a temperature of 39.5°C who is drinking, playing and interacting is usually less concerning than one at 38.2°C who is floppy, grey and difficult to rouse. How someone looks and behaves matters more than what the thermometer says.

Treating a fever with paracetamol or ibuprofen is about making someone comfortable enough to drink and rest. It does not shorten the illness, and there is no need to chase the number down.

Common causes

• Viral upper respiratory infections — by far the commonest, and needing no antibiotics
• Tonsillitis and throat infections
• Chest infections
• Urinary tract infections, which in older people can present as confusion with little else
• Gastroenteritis
• Ear infections, particularly in children
• Glandular fever in teenagers and young adults, where fever runs for a fortnight or more
• Cellulitis and other skin infections

Less common but important

• Sepsis — an overwhelming response to infection, which can develop from any of the above
• Malaria and other travel-related infection — always mention recent travel, even months later
• Inflammatory conditions rather than infection
• Drug fever, from a recently started medication
• Persistent unexplained fever over weeks, which needs proper investigation

A video consultation can assess a fever surprisingly well in most cases, because the important information is how the person looks, how they are behaving, how they are breathing and whether they are drinking — all of which are visible.

What we cannot do is examine. We cannot listen to the chest, look in an ear or a throat, or feel an abdomen, and there are presentations where those findings decide the outcome. Where that applies, the GP will say so early and direct you to in-person care rather than working around it.

What the consultation covers

• Systematic screening for the warning signs above, which is the main clinical value and takes only a few minutes
• Finding the source — the pattern of associated symptoms usually identifies it
• Whether antibiotics are actually indicated. Most fevers are viral, and antibiotics for those cause side effects and drive resistance without helping. Where a bacterial infection is genuinely likely, a prescription is issued the same day
• Practical advice: fluids matter far more than the temperature reading; paracetamol or ibuprofen for comfort rather than to force the number down; and there is no need to alternate them routinely or to wake someone to medicate them
• Clear safety-netting — exactly what to watch for and precisely when to call 999, which is the single most useful thing to take away from a fever consultation
• Blood tests where fever is prolonged or unexplained, and travel-related assessment where relevant

How high is too high?

The number matters far less than how the person looks and behaves. A child who is alert, drinking and playing at 39.5°C is less worrying than a drowsy, floppy child at 38°C. Doctors assess fever by how unwell someone is — their breathing, alertness, colour and fluid intake — not by the reading.

The exception is age: any fever in a baby under three months needs same-day assessment, whatever the number and however well they seem.

Should I alternate paracetamol and ibuprofen?

Not routinely. Use one, at the correct weight-based dose. Only consider the other if the first has not helped and your child is still genuinely uncomfortable. Alternating is where dosing mistakes happen — and the aim is comfort, not a normal thermometer reading.

Can a high fever cause brain damage?

No. This is one of the most persistent and most distressing myths in parenting. Ordinary fevers from infection do not cause brain damage — the body regulates them, and they do not climb indefinitely. What causes harm is the underlying infection in the rare cases where it is serious, which is why we assess the child rather than the temperature.

My child had a fit with the fever.

Frightening to witness, and usually far less serious than it looks. Febrile convulsions affect a small proportion of young children, are typically brief, and do not cause brain damage or epilepsy. Put them on their side, do not put anything in their mouth, and time it. Call 999 for a first fit, or any fit lasting more than five minutes.

Should I tepid sponge them?

No — that advice has been withdrawn. Cooling the skin causes shivering, which generates heat and raises the core temperature while making the person feel considerably worse. Ordinary clothing and a normal room temperature is right; neither wrapping up nor stripping cold.

Does teething cause fever?

Not a significant one. Teething may raise the temperature very slightly, but it does not cause a genuine fever — and attributing one to teething is a recognised way that infections get missed in babies. If your baby has a real fever, look for another cause.

Do I need antibiotics?

Usually not. Most fevers are viral, and antibiotics do nothing for them while causing side effects. What matters is identifying the minority that are bacterial — which is done by assessing how unwell someone is, not by how high the fever runs or how long it has lasted.

I've just come back from abroad and I have a fever.

Treat it as malaria until a blood test says otherwise if you have been anywhere malarious in the past year — even if you took your tablets, and even if the main symptoms are diarrhoea and vomiting. Malaria is regularly mistaken for a stomach bug or flu, and it can kill within 24 hours. Go the same day and say where you have travelled.