“Botulinum products have benefits but also can cause serious problems so it’s important that anyone who administers or receives these products understand the risks involved.”

Dr. Ellis Unger, acting deputy director of the Food and Drug Administration office that evaluates Botox, told reporters. No definitive reports of serious harm have been seen when the injections are given at approved doses for cosmetic purposes, such as smoothing wrinkles between the eyebrows, Unger said. Botox is a blockbuster product with 2008 sales topping $1.3 billion.

Botulinum toxin can relax or paralyze muscles and is used to smooth wrinkles and to treat conditions ranging from neck spasms to underarm sweating. In some cases, the toxin can spread to other parts of the body.

Possible complications include muscle weakness, trouble breathing or talking, blurry vision and loss of bladder control, the FDA said. “The hospitalizations are very few. Deaths are very rare, but they have been reported.” unger said.