Hello, Thanks for letting us know your health concern. It is true that Regestrone is the common brand name that is used to postpone periods. The dosage depends on the proximity to your natural period, your body weight and the duration of postponement needed. Usually twice or thrice daily dose of 5 mg. is advised. higher doses may cause side effects like vomiting, dizziness, breast tenderness, rashes etc., and sometimes may cause breakthrough bleeding. Please ask your health care provider for your appropriate dose. The dose should be continued until you need it or for a maximum of two weeks. Withdrawal bleeding is usually seen 3-7 days after the completion of the course. Hope this helps.