Several sexual enhancement supplements were recalled this week because the products contain undeclared drugs, according to the Food and Drug Administration.

The products, called Vicerex and Black Ant, manufactured by American Lifestyle, are marketed as enhancing sexual desire and performance.

Vicerex was found to contain the drug tadalafil (sold under the brand name Cialis), and Black Ant was found to contain the drug sildenafil (brand name Viagra). Both tadalafil and sildenafil are FDA-approved drugs to treat erectile dysfunction.

Supplements are not allowed to contain prescription drugs. Tadalafil and sildenafil can cause adverse effects (such as dangerously low blood pressure) if taken along with other prescription drugs that contain nitrates, the FDA said.

The recall is voluntary, and no adverse events have been reported so far.

Consumers should return the product to the place of purchase or to American Lifestyle. The UPC codes for the recalled products can be found on the FDA release.

Earlier this month, the FDA warned consumers that a number of other sexual enhancement supplements contained undeclared drugs.

The FDA regulates supplements only after they enter the market. Because of this, consumers should be careful about purchasing supplements, particularly sexual enhancement, weight loss and bodybuilding supplements, because the agency is not able to test all of them.

Some supplements are certified by the U.S. Pharmacopeial Convention or NSF International — these certifications can provide reassurance that the products contain the proper dosage of ingredients, and don't contain prohibited ingredients, experts say.

Follow Rachael Rettner @RachaelRettner. Follow MyHealthNewsDaily @MyHealth_MHND, Facebook & Google+. Originally published on MyHealthNewsDaily.