Botox injection is the fastest-growing sector of cosmetic surgery in the US following its approval by the US Food and Drug Administration last April.

Botox - short for ‘botulinum toxin A’, a neurotoxin produced by the bacterium Clostridium botulinum that causes food poisoning - stops wrinkling when injected into the skin. However, as it is a very potent poison, there are fears that it could be developed for use in bacteriological warfare.

Cosmetic surgeons try to reassure women that botox cannot spread beyond the site of injection but, as US biochemist Dr Nicholas Abrishamian recently told The Lancet: 'When you inject anything anywhere, the lymphatic system picks it up and takes it in systemically. There’s no way that it stays in one spot only.'

This idea is amply supported by the tally of side-effects reported to date, of which headache, respiratory infection and nausea are only the mildest. Severe difficulty in breathing and swallowing have also been experienced by women with preexisting neuromuscular disorders. There have also been rare reports of heart arrhythmias and even heart attacks - some of them fatal.

Dr Abrishamian warns of even more sinister side-effects. 'About 5 per cent of my MS [multiple sclerosis] patients have had Botox injections,' he says. 'I can’t prove the Botox/MS connection, but I’m concerned' (Lancet, 2002; 360: 929).