The non-prescription products are Bayer Women’s Low Dose Aspirin + Calcium and Bayer Aspirin with Heart Advantage, which contains plant-based substances called phytosterols, the Food and Drug Administration said in a statement today. The agency has also sent warning letters to the company.

Dietary supplements generally don’t need FDA approval. The agency is responsible, though, for approving new drugs and has in the past warned companies they need clearance to sell products that combine the two. The regulators focused on the Heart Advantage product after it was introduced this year.

“The marketing of these unapproved drugs is troubling,” said Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research, in a statement. “The overuse or misuse of these aspirin-containing products can put consumers at risk for internal bleeding and other adverse events.”

The FDA isn’t aware of harmful side effects from the products, the agency said in its statement.

Bayer, of Leverkusen, Germany, gained 63 cents, or 1.6 percent, to 38.52 euros at 1:52 p.m. New York time today in Frankfurt trading. The shares have lost 38 percent of their value this year, compared with a 13 percent decline in the Bloomberg Europe Pharmaceutical Index.

Bayer’s Response

Bayer “stands behind the marketing of both products,” said Anne Coiley, a Bayer spokeswoman, in a telephone interview. The products contain language telling consumers to consult with their doctors, she said. The company will review the warning letters and respond to the FDA, she said.

The FDA said the products’ combination of aspirin and the supplements — along with their beneficial health claims — cause them to be classified as new drugs, requiring agency approval.

The FDA began examining Heart Advantage after it was introduced earlier this year, said Michael Levy, acting assistant director of compliance in the FDA’s drug division. The agency was especially concerned about that product because “it is a combination that we have not seen before,” Levy said in a telephone interview.

Other Product Review

The FDA also decided to examine the women’s aspirin, introduced in 2002, “in the interest of consistency,” he said.

The calcium in the women’s aspirin is intended to help against osteoporosis, a bone-thinning disease, while the phytosterols are intended to lower the bad form of cholesterol.

Aspirin can be combined with calcium for use in buffered aspirin, according to the agency. When combined to make an aspirin product that claims to fight osteoporosis, the product becomes a new drug that needs FDA approval, according to the agency.

Companies that don’t resolve FDA violations raised in warning letters risk sanctions such as injunctions or seizures, according to the FDA.

Two House Democrats — Representatives John Dingell and Bart Stupak of Michigan — wrote to the Health and Human Services Department, which oversees the FDA, on Oct. 14 questioning whether the Heart Advantage product violates agency rules. They cited a May 2000 letter from the FDA saying that the agency recommends that companies refrain from marketing products that combine drugs and dietary supplements.