Hi. Thanks for asking in Healthcare Magic. All OCPs contain hormones and will result in hormonal imbalance by interfering with the existing hormonal status of the body. So depending upon the individuals, it will take some time, usually 3 to 6 months, for establishment of the regular cyclical pattern of menstruation. One of the main side effects of the pills is irregular bleeding and bleeding between periods. Your nausea, cramping and irritability are due to the action of progesterone in the pill. You should complete all the pills in the pack and should not stop if the bleeding starts. Mistaking the bleeding/spotting before the completion of the pack and stopping the pills will interfere with the next cycle and will also abolish the contraceptive effect of the pills. OCPs are available in different combinations with various strengths. If you still have these side effects after few cycles, then you can consult with your treating Dr. for a different type of pill. Usually progesterone alone pill or mini pill causes these problems but you have not mentioned the type of pill you are taking. Either go in for a combination pill or if you are already taking one, then go for pill with higher estrogen dose. Your treating Dr will know about these preparations. I hope this is useful to you.