Most chest infections in otherwise healthy adults are viral, and antibiotics make no difference to them.
Two things people believe that are not true:
- Green or yellow phlegm does not mean a bacterial infection. The colour comes from your own immune cells, and it is just as common in viral illness. This single misconception drives an enormous amount of unnecessary antibiotic prescribing
- A cough lasting three or four weeks is normal after a chest infection. The airways stay irritable long after the infection has gone. It is not a sign the antibiotics failed
What genuinely suggests something needing treatment: a high fever that persists, breathlessness at rest, chest pain on breathing in, coughing blood, being unable to keep fluids down, confusion, or getting better and then suddenly worse.
The honest limitation of a remote consultation is that we cannot listen to your chest or measure your oxygen level. Where the story suggests pneumonia, we will arrange in-person assessment rather than treat blind.
A cough lasting more than three weeks needs a chest X-ray in anyone over 40, particularly a smoker or ex-smoker — that is a NICE recommendation and it is how early lung cancer gets found.