Hi. Thanks for asking in Healthcare Magic. Trigestrel is a triphasic oral contraceptive pill with three different doses of estrogen and progesterone (brown, white and yellow pills) and non hormonal red pills. Generally OCPs are started on the first day of menstrual cycle with non hormonal pills (red pills). But, since you have completed your periods, you should start with the brown pills (6 in number) and take it continuously, one on each day for 6 days, followed by 5 white tablets, then 10 yellow tablets and finally 7 red inactive tablets. You should take the tablets exactly on the same time every day. Never miss the tablet. If you happen to miss one tablet, take 2 on the next day at the usual time. If you miss more than 2 tablets, then you should discontinue the strip and use another contraceptive method till you get your period and restart with red inactive pills on the first day of period. You should not stop the pill if you get bleeding/ spotting while taking the pills. Some of the antibiotics and other drugs will interfere with the action of OCP and will result in contraceptive failure. So don t take any self medication without consulting your treating Dr. I hope this is useful to you.