PARSIPPANY, N.J. — Glaxo­Smith­Kline Consumer Healthcare is warning consumers that a small quantity of a fake weight-loss product, falsely packaged and labeled as alli, has been sold on eBay and other auction web sites.

The company said that the Food and Drug Administration, which issued an alert this week, has reassured the public that "there is no evidence at this time that counterfeit alli products have been sold through other channels, such as retail stores."

The falsely packaged and labeled products are the 60-mg, 120-count refill packs only. The fake products are sold on online auction sites directly to consumers and are falsely presented as the genuine alli product, according to GSK.

This FDA photo shows that the contents of the real alli product (left) are pellets, while the counterfeit item (right) contains a powdery substance.

Preliminary testing confirms that the counterfeit products do not contain the active ingredient orlistat, which is found in the authentic alli product, and that the prescription drug sibutramine has been detected in the fake product, GSK said.

Sibutramine, the active ingredient in the prescription drug Meridia, could interact with other medications that consumers may be taking, and there are dosing differences between alli (three times a day) and Meridia (once a day), GSK noted.

The company stated that although many of the counterfeit products may look similar to its products, "they are illegal and have no connection with GSK or the FDA." GSK and the agency have initiated efforts to identify those responsible for the counterfeit products.

The authentic alli expiration date includes only the month and year, and the seal on the bottle should read “SEALED FOR YOUR PROTECTION” in white ink on the GSK alli bottle — a statement that is not present on the fake product, the company said.

In addition, the fake product has a larger capsule size and its content is powdery, whereas the genuine capsules contain small pellets. The outer cardboard packaging on the counterfeit item also is missing a "lot" code, and the fake product has a slightly taller and wider cap with coarser ribbing than the genuine product.