Is it safe to take diet pills while on birth control?

Dear Ask The Doctor: Is it safe to take diet pills while on birth control?

Dear Kris: Most studies have found that diet pills and oral contraceptives do not interfere with each other. However, you should be careful when you purchase diet pills. Xenical (Orlistat) is the only weight loss drug approved by the Food and Drugs Administration (FDA). Diet pills can cause some side effects at times, like diarrhea or vomiting. In such cases, your birth control pill will be expelled before it is absorbed in the body.