In April 2009, the FDA ordered a “black box” label for all Botox and similar products — the strongest drug-packaging warning that the agency can require. The label now states that the toxin can potentially spread beyond its injection site to other parts of the body and cause symptoms of botulism, including muscle weakness and trouble breathing or swallowing.

The FDA move was prompted by reports of serious health problems and a number of deaths arising from the unapproved use of the toxin in treating certain medical conditions, especially spastic limb movements in children with cerebral palsy. The agency emphasized that spread of the toxin to other body sites is not a danger when Botox is used at approved doses for cosmetic purposes. The FDA also warned that toxin potency can vary among products, so doses, which are expressed in “units,” aren’t necessarily interchangeable from one product to another.

Finally, if you’re considering botulinum toxin injections for any reason, cosmetic or medical, the standard caveats apply: Look for a licensed, board-certified physician who has extensive experience with botulinum toxin and its potential side effects.

Don’t be afraid to ask questions. Request permission to speak to a patient the clinician has treated. And before treatment, be sure to tell your physician about any prescription or over-the-counter medications you’re taking, as well as anything you’re allergic to and any medical problems you might have.