Does every fever need an antibiotic?

When we get a fever, many of us first think of the tablet that “worked last year”. That is natural: a fever is unpleasant and we want it over quickly. But a fever is only a sign, not the illness itself. The body heats up when fighting a virus, a bacterium and sometimes things that are not infections at all, and an antibiotic targets only one of these.

What do antibiotics work on?

The CDC states clearly: antibiotics treat only certain bacterial infections, such as strep throat, whooping cough and urinary tract infections. They do not work on viruses. Colds, flu and most sore throats and coughs are viral. The NHS also says these medicines do not work for colds, flu and most coughs.

Some bacterial infections also clear without medicine. The CDC mentions some sinus and ear infections. So even “bacterial” does not always mean “a medicine is needed”. The NHS says a doctor usually gives an antibiotic when the infection is unlikely to clear on its own, would take too long, carries a risk of serious complications, or could spread to others.

What happens if I take one when it is not needed?

The CDC says an antibiotic that was not needed does not help you, and its side effects can still harm you. These can be minor (rash, dizziness, nausea, diarrhoea) or serious, such as a bowel infection with severe diarrhoea that damages the large bowel.

Another problem is antimicrobial resistance. WHO counts incorrect and unnecessary use of antibiotics as one of its main causes. It is the germ that becomes resistant, not your body, but the result is that future infections become harder, and sometimes impossible, to treat (CDC). When that happens, stronger medicines with more side effects may be needed.

Why is “take it first, see later” wrong in a prolonged fever too?

For a fever that goes on for several weeks, the doctor looks for the cause. The clinical source AAFP says that a trial of antibiotics for a prolonged fever has no proven benefit and may delay finding the real cause, except in people with very weak defences or who are seriously ill, where the doctor decides otherwise. The cause of a prolonged fever is also not always an infection.

So what should I do when I have a fever?

For adults with a fever, the NHS says to rest, drink plenty of fluids (your urine should be pale yellow and clear), and stay at home while you have a fever. If you are uncomfortable, take a medicine to bring the fever down after talking to a doctor or pharmacist.

Tell a doctor early if:

• you are looking after the fever at home and it is not getting better or is getting worse
• the fever is very high or will not come down
• the fever comes with confusion, fast breathing, blue or mottled skin, severe shivering, a rash that does not fade when pressed, or a stiff neck. In that case call 115 (Iran’s emergency number)

For the third one, do not wait for a routine appointment.

If the doctor gives an antibiotic

Take it exactly as directed. The CDC says not to take medicine prescribed for someone else, not to save antibiotics for later and not to share them. The NHS also says not to borrow them from a friend or acquaintance. Do not stop the course without the doctor’s advice; the details are in the guide on using antibiotics correctly.

In short

A fever should not be brushed off, but not every fever needs an antibiotic. The best step is to find the cause. What medicine you need, or do not need, is for the doctor to decide after an examination.