You might have thought that Botox, the popular drug made from botulinum toxin, was simple spot treatment for everything from frown lines to muscle spasms. But studies have shown that the effects of the drugs can actually spread throughout the body, causing difficulty swallowing and breathing and even death. Acting on this mounting data, the U.S. Food and Drug Administration (FDA) announced strict new labeling requirements for Botox and similar products yesterday, reports The New York Times.

The drugs are manufactured from the botulinum toxin, which is a toxic protein associated with botulism, the disease that can result in paralysis and death. In a controlled dose and purified form, the toxin was approved by the FDA in 1989 to treat crossed eyes and eyelid twitching, in 2000 to treat abnormal pain or twitching in the neck (cervical dystonia) and in 2002 to treat frown lines. It's also approved for use to mitigate excessive armpit sweating.

In a 2005 paper the Journal of American Academy of Dermatology alerted the FDA to 28 deaths from noncosmetic uses of Botox, and a January 2008 petition to the FDA from Public Citizen, a nonprofit public-interest group, called for stricter regulation of the drug, pointing to adverse reactions, deaths and the European Union's firmer warnings. Nineteen days later, the FDA acknowledged the data (noting, however, that the worst cases were from unapproved uses of the drug, particularly those in children to treat limb spasms associated with cerebral palsy) and promised to review the products' safety.

Yesterday's decision comes as a result of this review, in which the FDA found evidence of even more adverse reactions and deaths. The new warning—dubbed a "black-box warning" due to its severity—will note "the risk of adverse events when the effects of the toxin spread beyond the site where it is injected," according to the FDA's Web site. The FDA will also require manufacturers to provide information to doctors and patients about the risks.

The decisions comes just two days after the FDA approved a newer and less costly form of the drug called Dysport, which is manufactured by Ipsen and is already on the market in Europe. The Times reports that Botox, made by Allergan, reported sales of $1.3 billion across the world last year.

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