On December 17, the U.S. Food and Drug Administration (FDA) warned people against using nearly 50 dietary supplements sold on Amazon, eBay, and other retailers.

The products, which were sold as sexual enhancement and weight loss supplements, were found to be tainted with undeclared active pharmaceutical ingredients, including some prescription drugs, which could pose serious risks to consumers.

The U.S. drug regulatory body purchased and tested sexual enhancement and weight loss supplements that were sold on Amazon, eBay, and other websites.

Upon examination, the agency found that the supplements contained a few potentially dangerous drugs that could cause serious side effects or drug interactions.

The federal law advises dietary supplement manufacturers to accurately state the product’s ingredients on their label. Under that law, the products cannot contain prescription drugs.

Donald Ashley, Director, Office of Compliance, FDA’s Center for Drug Evaluation and Research, said, “While the FDA has engaged in discussions with online marketplaces like Amazon and eBay regarding these issues in the past, we believe they can do more to protect consumers from these fraudulent and potentially dangerous products.”

The agency has been urging people to avoid the supplements it cited.

Ashley Settle, a spokesperson for eBay, told Consumer Reports that the company has currently been reviewing its site and will remove the products tainted with undeclared drugs.

A spokesperson for Amazon said the company is examining the FDA’s information and it will take action accordingly.

In June, the FDA published the contents of “59 bitter orange supplements and found illegal stimulants in almost 10 percent of the products,” according to Consumer Reports.

In September, Harvard University researchers reported that they found undeclared prescription drugs in popular “nootropic” supplements, which are sold as smart drugs that boost brain function.

In the latest testing, the FDA said all 26 products bought on Amazon and 20 products bought on eBay contained undeclared prescription drugs, such as sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra).

The agency also found drugs like sibutramine (an appetite suppressant), desmethylsibutramine (an analog of sibutramine), and fluoxetine (an antidepressant).

“Many of these are active ingredients for use in FDA-approved prescription drugs,” the FDA said, which are restricted to use under the supervision of a licensed health care professional.”

The FDA also said that some of those products purchased on Amazon were designated on their listings as “#1 Best Seller” or “Amazon’s Choice.” The

The Amazon spokesperson told Consumer Reports that vendors must follow all applicable laws and regulations when listing items for sale.

“We have proactive measures in place to prevent prohibited products from being listed and we continuously monitor our store,” the spokesperson said. “Those who violate our policies are subject to action including potential removal of their account.” Meanwhile, if you are considering using such supplements, please check with your doctor first.