The FDA warned consumers Friday not to use two unapproved Brazilian diet pills because testing has revealed they may contain tranquilizers, antidepressants and stimulants.

The pills are sold over the Web as Emagrece Sim, or the Brazilian Diet Pill, and Herbathin, the Food and Drug Administration said. The pills are billed as all-natural but may contain active ingredients, including controlled substances, normally found only in prescription drugs like Librium and Prozac.

Their use can lead to serious side effects or injury, the FDA said. The active ingredient in Librium, chlordiazepoxide, can be habit-forming.

"There are dangers to consumers who purchase diet pills that contain drugs of unknown origin and quality," said Dr. Steven Galson, director of the FDA's center for drug evaluation and research.

Find out more about the dangers of Brazilian diet pills at http://abclocal.go.com/ktrk/story?section=health&id=3820599.