Sexual enhancement supplements – like those reportedly taken by Lamar Odom before he collapsed at a Nevada brothel – are often spiked with powerful and hidden pharmaceuticals, despite labels claiming they only contain herbs and other natural ingredients, experts and regulators have warned for years.

Odom took cocaine and as many as 10 sexual–performance supplement pills leading up to his hospitalization in Las Vegas, according to a 911 call released Wednesday by the Nye County Sheriff’s Department. The product he took was “Reload; 72-hour strong; sexual performance enhancer for men,” two employees of the Love Ranch said on the 911 call.

In 2013, the FDA issued a public warning that consumers should not purchase or use a supplement called Reload because tests found it contains sildenafil, the active ingredient in the prescription erectile dysfunction drug Viagra. The undeclared ingredient may dangerously interact with other drugs, especially nitrates often taken by men with diabetes, high blood pressure or heart disease, the FDA warned.

A photo of the product that the FDA posted with its safety alert included no information about what company made the product. Despite the product’s label claiming it was made in the USA, the website listed on it appears to be a Japanese dating site that provides little clue as to who is the maker of the product.

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It’s rare for supplements taken by consumers to undergo testing by the FDA. Out of an estimated 85,000 supplement products on the market, the FDA told USA TODAY in 2013 that it was budgeted to run just 1,000 tests per year.

Under the Dietary Supplement Health and Education Act of 1994, known by its acronym DSHEA, the FDA must show a product is unsafe before it can take any action to restrict its use or seek its removal from the market.

Products marketed as nutritional supplements – which range from vitamins and minerals to protein powders to herbal blends – are treated like foods and presumed to be all-natural and safe, unless proven otherwise. Although supplements are often sold and used as remedies to treat various conditions, they aren’t required to prove their safety or effectiveness before being sold, as is required for medications.

USA TODAY’s “Supplement Shell Game” investigation in 2013 found it difficult or impossible to determine who the people or companies are behind many of the drug-spiked supplements detected through a limited testing program run by the U.S. Food and Drug Administration. When companies could be identified, USA TODAY found that many of those caught selling spiked supplements are run by people with criminal backgrounds and regulatory run-ins. Consumers buying products from these firms were in some cases entrusting their safety to people with rap sheets involving  barbiturates, crack cocaine, Ecstacy and other narcotics, as well as arrests for selling or possessing steroids and human growth hormone. Other supplement company executives had records of fraud, theft, assault, weapons offenses, money laundering or other offenses, the investigation found.

Read USA TODAY’s Supplement Shell Game series at supplements.usatoday.com