It’s called Reumofan, and many US residents swear by it as a source of relief for arthritis and joint pain.

P>But this dietary supplement from Mexico is raising plenty of red flags, according to USA Today, which conducted an investigation into the pill.

The newspaper reported that Riger Natural, the company that makes the pill, seems shady, at best. Riger Natural "uses fake addresses, lies about the ingredients in its products and may not even exist," the newspaper reported.

USA Today said it set out to visit the addresses the company listed as its locations, but found those addresses to be fakes. The newspaper also said that retailers that have in the past distributed Reumofan say the representatives with whom they dealt with just disappeared.

"Even Mexican health authorities have been unable to track down the company," the report states.

"Meanwhile, US consumers – desperate to curb arthritis and joint pain – continue to buy Reumofan over the Internet and by crossing the border," according to the article. "And they are playing a dangerous game with their health."

"Dozens of Reumofan users have suffered serious and sometimes life-threatening health effects after taking the pills, including liver injury, strokes, and severe episodes of bleeding," the newspaper said, adding that at least three reports about serious side effects tied to the supplement involve deaths.

The newspaper report called into question the supposed natural ingredients of Reumofan, which include shark cartilage, white willow, and glucosamine.

But US and Mexican lab tests found "up to three powerful and potentially dangerous prescription drugs hidden in Reumofan products."

FDA officials, meanwhile, say they are investigating the product and company.

"As an open investigation, there’s not much we can really say about who actually was responsible for putting the product into commerce," Daniel Fabricant, director of FDA’s dietary supplement division, said.

The FDA has issued warnings about the pill.