Botox approved for crow's feet

US government regulators for the first time have approved Botox injections to treat crow's feet.

The Food and Drug Administration said on Wednesday that Allergan's Botox Cosmetic injection is the first drug approved to treat the wrinkles that form on the outside edge of the eyes.

Allergan studied the use of the drug in 833 adults with crow's feet who randomly received Botox or a sham injection. Patients who received Botox had fewer visible wrinkles than those who received the placebo drug.

The most common side effects seen in patients were swelling and excess liquid around the eyelids.

The drug works by blocking the connections between nerves and muscle, temporarily paralyzing muscles to make wrinkles less prominent. The drug is a purified form of botulinum, one of the most toxic substances in the world.