Hi, Thanks for using the HCM. I am happy to address your questions, mercilon is an oestrogen/ progestogen combination oral contraceptive that inhibits ovulation. 21 larger white tablets with active medication and 7 smaller white tablets that do not contain any active ingredients. Tablet-taking has to start on day 1 of the woman s natural cycle (i.e. the first day of her menstrual bleeding). Starting on days 2-5 is allowed, but during the first cycle a barrier method is recommended in addition for the first 7 days of tablet-taking. One tablet is to be taken daily for 28 consecutive days. The first tablet should be taken from the blister in the green section of the calendar pack marked with the appropriate day of the week. During the placebo days a withdrawal bleed usually occurs. This usually starts on day 2-3 after the last active tablet and may not have finished before the next pack is started. No reports of serious deleterious effects except nausea, vomiting and possible slight vaginal bleeding, if too serious will recommend you discuss with your clinician for alternate medications. Hope I have answered your query. If you have any further questions I will be happy to help. Thanks