San Francisco, Dec 30 (IANS): The US Food and Drug Administration (FDA) has warned Amazon to act on men's energy or health supplements that carry active pharmaceutical ingredients (API) tadalafil and sildenafil that are used to treat erectile dysfunction (ED).

In a letter to Amazon CEO Andy Jassy, the agency listed seven different products available on the e-commerce platform with ingredients found in Viagra and Cialis.

"This letter concerns your firm's distribution of products that violate the Federal Food, Drug, and Cosmetic Act. The FDA purchased on your website products that are labeled as energy enhancing supplements or food, but laboratory analyses confirmed that they contained undeclared and potentially harmful active pharmaceutical ingredients," the agency said.

An Amazon spokesperson told The Verge that the products were removed from the website before the FDA letter.

FDA purchased "MANNERS Energy Boost", "Round 2", "WeFun", "Genergy", "Big Guys Male Energy Supplement", "Mens Maximum Energy Supplement", and "X Max Triple Shot Energy Honey" on Amazon.

The FDA confirmed through laboratory analyses that the products contained the active pharmaceutical ingredient (API) tadalafil and sildenafil.

These ingredients are not declared on the products' labelling.

"Sildenafil and tadalafil are phosphodiesterase type-5 (PDE-5) inhibitors and the active ingredients in the FDA-approved prescription drugs Viagra and Cialis, respectively, used to treat erectile dysfunction (ED)," the agency wrote in the letter. These undeclared ingredients may interact with nitrates found in some prescription drugs, such as nitroglycerin, and may lower blood pressure to dangerous levels.

Consumers with diabetes, high blood pressure, or heart disease often take nitrates. Information on the labels demonstrates that these products are marketed as dietary supplements.

"However, these products do not meet the definition of 'dietary supplement'," said the FDA.

The FDA asked Amazon to investigate and determine the causes of any "violations and to prevent their recurrence or the occurrence of other violations".

"It is your responsibility to ensure that your firm complies with all requirements of federal law, including FDA regulations," the agency said.