Hi, Your doctor must have prescribed Diane to treat acne and hirsutism associated with PCOD. Diane contains ingredients similar in action to hormonal birth control pill. Cyproterone acetate contained in it is a progesterone derivative and ethinylestradiol present in it is a synthetic estrogen. So this tablet is also a effective combined hormonal contraceptive. It is as effective as any other combined hormonal pill. Therefore if you have been using this pill correctly as per the instructions there is no need to use emergency contraception. However there is a very small possibility of method failure as in birth control pill. So if your periods get delayed get a pregnancy test done. I advise you to use barrier method of contraception like condom along with Diane to protect yourself from sexually transmitted diseases. I hope I have answered to your satisfaction. If you have any further queries do contact me through healthcare magic