The government agency has also advised field staff to be on the look-out for shipments of Emagrece Sim, also known as the Brazilian Diet Pill, and Herbathin.
Both products are made in Brazil by Fitoterapicos and Phytotherm Sim. Since the Emagrece Sim name was not protected, it appears to have also been used on products made by other companies and there is no guarantee that the formulas are the same.
According to reports, products can cost as much as $230 for one month's supply.
The pills tested by the FDA were found to contain Chlordiazepoxide, a drug used to control anxiety and alcohol withdrawal which may be habit forming; Fluoxetine HCI, an anti-depressant used in Prozac which has been linked to several serious drug interactions and adverse effects; and an amphetamine precursor called Fenproporex which is not approved for marketing in the US. Fenproporex may also cause urine tests for amphetamines to show up as positive.
"There are dangers to consumers who purchase diet pills that contain drugs of unknown origin and quality," said Dr Steven Galson, director of FDA's Center for Drug Evaluation and Research. "These products are not approved by FDA and if people experience side effects, it is difficult to trace problems and for physicians to treat them."
FDA has identified distributors in Miami, but the Internet is a fertile ground for the sale of diet pills, so it is important that consumers be on their guard.
A Google search shows up around 65,400 results for Emagrece Sim, and HerbaThin 281. However some of these are postings by concerned consumer groups who became aware of a potential problem last year.
The negative over these products has caused other Brazilian supplement makers to defend their own products.
Dr Vital Fill, author of Lose Weight the Brazilian Way and producer of Maxilean diet pills has condemned the use of appetite suppressant pills containing harmful ingredients and will hold a press conference on the subject this week.