Some arthritis patients swear by the effectiveness of the dietary supplements Reumofan Plus and Reumofan Plus Premium, but the U.S. Food and Drug Administration (FDA) says the products actually contain prescription drug ingredients not listed on the label. These active ingredients can be potentially harmful to users, and the FDA is advising consumers using either supplement to see a doctor immediately. One of the chief concerns is the presence of a corticosteroid in Reumofan Plus that, if stopped abruptly, could result in harmful withdrawal symptoms.

In a safety alert, the agency potentially linked use of Reumofan Plus with severe side effects, including death and stroke. Other reported health problems in those using the two products included liver injury, severe bleeding, alterations in blood sugar levels, weight gain, swelling, leg cramps and adrenal suppression.

“[The] FDA has received at least two reports of death and one of stroke in consumers who had used Reumofan Plus,” says Sarah Clark-Lynn, a press officer for the FDA. “Based on the limited information provided in the reports, assessments regarding causality or other contributory factors could not be evaluated.”

The products, manufactured by Riger Naturals, located in Mexico, were sold in retail outlets as well as on popular Internet sites such as eBay and Amazon. They are billed as “100% Natural” and claim to contain ingredients such as white willow, eastern teaberry and Holm oak, as well as vitamins and minerals.

But lab tests on Reumofan Plus found the prescription ingredients dexamethasone, a corticosteroid; diclofenac, a prescription nonsteroidal anti-inflammatory drug; and methocarbamol, a muscle relaxant. Tests on Reumofan Plus Premium found diclofenac and methocarbamol.

Clark-Lynn says the agency first issued a warning about the potential danger of taking Reumofan Plus last June. Around the same time, the FDA reported that Mexican health authorities ordered Riger Naturals to recall the product. One distributor in the U.S. also issued a recall. But there still may be bottles of the product out there.

“Because this product is manufactured by a company in Mexico and distributed by a large number of small distributors in the United States, it is extremely difficult for [the] FDA to address all distributors that may be selling this product at retail and on the internet,” says Clark-Lynn.