TUESDAY, Jan. 22 (HealthDay News) -- U.S. Food and Drug Administration approval of Botox (onabotulinumtoxinA) has been expanded to include adults with overactive bladder who don't respond to a class of drugs called anticholinergics.

Overactive bladder's typical symptoms including leakage, frequent urination and feeling the sudden and urgent need to urinate. Botox, when injected into the bladder, causes it to relax and increases its capacity, the FDA said in a news release.

In a clinical study, people treated with Botox after 12 weeks had urinary incontinence 1.6 to 1.9 times less per day than people treated with a placebo, the FDA said.

The most common adverse reactions recorded during the study included urinary tract infection, painful urination and incomplete bladder emptying (urinary retention). People who develop urinary retention may have to use a catheter until the situation resolves, the agency said.

Botox has been approved for several other uses, notably to treat facial wrinkles. The product is made by Allergan Inc., based in Irvine, Calif.

More information

Medline Plus has more about overactive bladder.