CHICAGO (CBS) — Diet pills. Special coffee. Even certain dried fruit.

All of these products are supposed to help you lose weight.

But the Food and Drug Administration warns, they could cause a heart attack — or even kill you.

In this CBS 2 original report, Suzanne LeMignot uncovers how these illegal products are making it into Chicago every day in massive quantities.

At the Chicago International Mail Branch at O’Hare International Airport, up to 1.5 million mail packages from overseas are inspected each month.

Many contain diet pills, heading to small health food stores or to people who bought them over the Internet.

“We see hundreds of [bottles of pills] coming in per day,” said Brian Bell, of U.S. Customs and Border Protection.

Agents are seeing a tremendous rise in shipments of diet pills containing sibutramine shipped from China.

Since January, 750,000 pills containing sibutramine have been seized. Sibutramine is a potentially deadly appetite suppressant. It’s been banned by the FDA.

Lisa Misevicz, of the Food and Drug Administration, says sibutramine can cause strokes. There has been one reported death.

And the government warns that consumers have no idea what’s inside the pills.

U.S. Customs and Border Protection chemists are not just seeing sibutramine in diet pills. Lab tests have found it in dried fruit and even instant “slimming” coffee.

The dried fruit in question smells horrible.

Why would somebody eat it?

“Someone who’s really desperate to lose weight,” said Bell.

The labels often claim the products are all natural and make no mention of sibutramine.

The FDA and the U.S. Customs and Border Protection are working closely to stop the flow of sibutramine into the United States, since the substance was banned about two years ago.