The Food and Drug Administration Friday approved a new drug from Vivus Inc. to treat erectile dysfunction.

The approval of the drug, Stendra, is the first product approval for Vivus, based in Mountain View, Calif. The company is also awaiting an FDA decision on its proposed obesity drug Qnexa, which is expected about July 17.

Stendra is also known by its generic name avanafil. The drug falls into the same class as other erectile dysfunction treatments on the market such as Pfizer Inc.'s Viagra and Eli Lilly Co.'s Cialis. The drugs work by increasing blood flow.

An estimated 30 million men in the United States are affected by erectile dysfunction, the FDA said.

Stendra is a pill that patients take on an as-needed basis 30 minutes before sexual activity.

Researchers who studied Stendra have said the drug worked as early as 15 minutes in some patients, which is potentially faster than other marketed drugs.

The FDA said the most common side effects reported in clinical studies of Stendra included headache, redness of the face and other areas, or flushing, nasal congestion and back pain.

The drug's approval was based on three clinical studies that involved 1,267 patients for 12 weeks. A subset of patients were followed for up to an additional 40 weeks to evaluate potential safety problems.