Can minocycline prevent pregnancy? Or give irregular period cycles?

Are you on birth control pills? Antibiotics interfere with birth control pills and can decrease the effectiveness and often women will experience bleeding as a result of the drop in hormones. A woman CAN become pregnant while on the Pill and she is taking antibiotics without using condoms as back up! You should never stop taking an antibiotic before it is finished unless the doctor tells you to. Stopping to early can make the infection come back worse and it may make it resistant to antibiotics. If you are on the pill and you take antibiotics, you should use condoms for back up the whole time you are the antibiotics and for seven days after you finish. The bleeding will go back to normal once you stop taking antibiotics (within a few days) and will be back to normal the next cycle. No minocycline does NOT prevent pregnancy. A woman can still get pregnant even if she is on her period. The bleeding or "period" is not what makes you pregnant or keeps you from being pregnant. It is ovulation and the fertilization of that egg that makes you pregnant and it is possible to bleed and ovulate at the same time!

Your period being irregular does not always mean ovulation is. I wouldn't count on it to prevent pregnancy.