The Food and Drug Administration (FDA) is warning some drugs used for impotence may cause sudden hearing loss.

Erectile dysfunction including Viagra, Levitra Cialis and the blood pressure medication Revatio will now carry new warning labels about the potential risk of sudden hearing loss, reported WebMD.

According to the the FDA, since 1996, there has been 29 reports of sudden hearing loss among men who took these types of drugs.

The FDA's ear-and-nose specialist Dr. Robert Boucher said that hearing loss sometimes occurred within hours after using the drugs.

"We don't know enough to say that it's ironclad caused by the drugs, but we see enough to say we can't ignore it either," he told the AP.

The FDA say that more tests are needed to see why hearing loss is occurring.