Antibiotics are useless for treating the common cold yet more are prescribed for the condition than for any other ailment.

Now Swiss scientists have discovered that doctors have been wrong only in 80 per cent of cases. Antibiotics can help one in five sufferers who has a specific nasal infection, they have found.

Specialists fear the finding will justify the overuse of antibiotics, even though they are associated with a range of side effects and their widespread use has resulted in bacterial resistance to the current generation of drugs.

Microbiologist Richard Wise warns: "Using antibiotics more often for such a prevalent disease as the common cold will make things worse. The risks are too high and the benefits minimal."

Even the Swiss researchers have asked that their findings be treated with caution. "Upper respiratory tract infections are self limited diseases and even the most astute clinician cannot distinguish a cold due to bacterial infection from one with no bacterial involvement," they say.

The researchers, from University Hospital of Geneva, divided 300 cold sufferers into those receiving a placebo and those given co-amoxiclav, a broad spectrum antibiotic. Using a swab, they discovered that 61 had one of three nasal bacterial infections H influenzae, M catarrhalis or S pneumoniae which responded well to the antibiotic.

!AThe Lancet, June 1, 1996.