The U.S. FDA released an updated public health alert regarding counterfeit Alli being sold over the internet.

According to the FDA, here's what you need to know:

• Alli is an FDA-approved, over-the-counter weight loss drug.

• FDA lab tests have confirmed that counterfeit versions of the drug do not contain the FDA-approved active ingredient; rather, they are made with varying amounts of the stimulant sibutramine.

• Sibutramine can be particularly harmful to those who have a history of cardiovascular disease and can lead to elevated blood pressure, stroke or heart attack.

• The counterfeit drugs have been identified as Alli 60mg capsules (120 count refill pack)

If you take Alli, it's important that you check it for:

• Missing lot numbers on the outer cardboard packaging;

• An expiration date that includes a month, day and year-expiration dates on legitimate packages include the month and year only;

• A wordless inner safety seal-the real product contains the words "SEALED FOR YOUR PROTECTION" on its inner seal;

• Large capsules containing white powder instead of  small white pellets; and

• A taller bottle with a wider, coarser cap than real Alli packaging

See photos of counterfeit Alli next to the real thing.