The Idaho Board of Pharmacy and the U.S. Food and Drug Administration issued a warning that strong prescription drugs have been found in products marketed across the country as Chinese herbal remedies called Black Pearls or Chuifong Toukuwan.

The FDA said Friday that laboratory tests of the product detected therapeutic levels of indomethacin, an anti-inflammatory agent with serious side effects; hydrochlorothiazide, a potent diuretic; and the tranquilizer diazepam.The label and literature with the product does not declare the presence of those prescription drugs, listing only herbal ingredients, according to the federal agency.

Officials said people already on prescription medications for arthritis and high blood pressure may be at greater risk because of the possibility of overdose or drug interactions. The FDA advised people taking Black Pearls to stop, and those also taking other medications to see their physician.

It described Black Pearls as haock bags with labeling in Chinese characters. Each bag contains about 60 pills.

The FDA said the pills come from several sources outside the United States and usually enter the country illegally via air mail in small shipments to health food stores, oriental food stores or novelty shops, and sometimes directly to consumers.

Labeling for Black Pearls suggests they help alleviate arthritis, osteoarthritis, rheumatism, headache, paralysis, back neuralgia, bone pain, acute or chronic neuralgia, and other pain caused by rheumatism.