Colds are generally self-limiting, but complications can occur. The sheer number of colds makes it seem that complications are common, but only a minority develop such problems.

Flu is more severe and leads to a higher proportion of respiratory complications, particularly pneumonia. Flu rather than a cold is generally considered to be likely if symptoms start abruptly with sweats and chills, muscular aches, dry sore throat, cough and high temperature. Someone with flu may be bed-bound and unable to go about their usual activities. This does not happen with a common cold.

The complications of flu affect other body systems and include muscle inflammation, heart failure, myocarditis, toxic shock syndrome, encephalitis, Guillain-Barre syndrome and Reye’s syndrome – but these are rare.

Complications in pregnant women can include death of the woman and the unborn child, premature birth and lower than anticipated birth weight. In children, febrile convulsions, vomiting, abdominal pain and diarrhoea are also seen. These are all reasons to encourage the uptake of flu vaccination and prompting this whenever possible in those eligible is good practice.

The message that antibiotics are ineffective for most people with colds or flu is at the centre of public health campaigns but be prepared to deal with enquiries from patients who think otherwise. It is vital to avoid unnecessary use of antibiotics and prevent this resulting in antibiotic resistance. This is part of effective antimicrobial stewardship.