HOW LONG DOES IT TAKE?

For antibiotics to work: Two hours ANTIBIOTICS work by directly killing bacteria or slowing down their growth, so allowing your immune system to kill them for you.

‘In laboratory studies, the amount of bacteria can be reduced 1,000-fold in one to two hours,’ says Dr Kieran Hand, a consultant pharmacist at University Hospital Southampton NHS Trust.

‘How long they take to work in the body is harder to determine, as it depends how many bacteria were in the system, how active the immune system is and the site of infection.’

One obvious sign they’re working is relief of symptoms — but that doesn’t mean you’re better. ‘For example, half of pneumonia patients with fever will have normal temperature and breathing after three days, but their chest X-rays may look abnormal for several weeks,’ says Dr Hand.