Botox: Beyond cosmetic fixes

The procedure that revolutionized wrinkle treatment has myriad medical uses, many still experimental. What's the evidence?

At one time, most of us knew about botulinum toxin mainly as the source of deadly botulism food poisoning. Produced by the bacterium Clostridium botulinum, the toxin is one of the most lethal substances on earth. Ingested, it can paralyze muscles throughout the body, including those that control breathing. Yet on a smaller scale, the same mechanism can do a body good. Injected into muscle tissue, for example, botulinum toxin can ease debilitating spasms and pain.