common cold

The common cold is the familiar, mild illness almost everyone catches a few times a year — a stuffy or runny nose, sneezing, a scratchy throat and perhaps a mild cough. It settles in the nose and throat rather than deep in the lungs, which is why the chest usually feels fine and the whole thing clears up on its own within a week or so.

Medically it is a viral infection of the upper respiratory tract — the nose, sinuses, throat and voice box. More than two hundred different viruses can cause it, with rhinoviruses the most common, which is one reason there is no single cure or vaccine. The symptoms come not so much from the virus damaging tissue as from the body's own inflammatory response: swelling and mucus that try to flush the invader out.

Treatment is purely about comfort, because the immune system clears the virus by itself: rest, fluids, and remedies that ease congestion or sore throat. Antibiotics are useless against a cold and should not be used, since they fight bacteria, not viruses, and bring needless side effects.

A cold occasionally paves the way for a secondary problem — a sinus or ear infection, or in vulnerable people a chest infection — so symptoms that worsen after the first few days, or a high fever and breathlessness, deserve a fresh look rather than being assumed to be just the cold.