The Food and Drug Administration approved Allergan Inc.'s Botox to treat urinary incontinence problems.

While Botox is mostly known for treating wrinkles, it now can also be used to treat bladder overactivity in people who have  neurologic conditions such as multiple sclerosis and spinal cord injury, the FDA said.

Urinary incontinence associated with neurologic conditions can be difficult to manage, said George Benson, the FDA's deputy director of the Division of Reproductive and Urologic Products, in a statement. Botox offers another treatment option for these patients.

About 691 patients in two clinical trials were studied before the FDA approved Botox for its new use.

The drug works by injecting Botox into the bladder to help it relax and increase its ability to store urine, with the effects lasting up to nine months. The injection, performed using a cystoscopy, may require general anesthesia. The most common side effects  included urinary tract infections and urinary retention, which might require self-catheterization to empty the bladder, the FDA.

Allergan said urinary incontinence is a chronic condition affecting about 340,000 people in the U.S. who suffer from MS or spinal cord injuries. The current standard of care includes oral medications that are taken regularly, but it's estimated that  about 71 percent of people stop taking at least one medication within 12 months, it said. If oral medications fail, surgery may be considered, it added.

For people who do not respond to or cannot tolerate the side effects of an oral anticholinergic medication, Botox is a new long-lasting treatment option to reduce urinary incontinence episodes and address a particularly burdensome issue, said Scott Whitcup, Allergan's executive vice president of research and development and chief scientific officer.