How does taking Rifampin reduces the effect of I-pill?
Patient: dear Sir / ma am, I had sex sometime on 25 august and it was not unprotected. My partner used a condom. I took an ipill the next day.....but the cause of worry is that I am on tuberculosis medication for the past 7 months and I read earlier that the drug rifampin reduces the effect of the ipill. I even read that the dosage needs to be doubled so I took another ipill the next day. I am quite anxious? Is there a cause for worry....would there be a minute chance that I could be pregant? Kindly do get back to me as soon as possible. Thanks and regards Doctor: Hello,I have gone through your query and understood  the concern. It is true that Rifampicin reduces the contraceptive effect of hormonal contraceptives. If you had the intercourse during your safe period or non-ovulation period, you are naturally protected. Please note that ovulation occurs two weeks prior to the onset of the next period and this is the fertile period of the cycle. You have also had double protection and hence need not worry about failure. The excess hormone content in the pills can induce withdrawal bleeding and delay the next natural cycle by a week or two. Please see the specialist if you become overdue by ten days. Hope this helps.