Hi, Krimson contains both cryproterone and ethinyl estradiol which is used to treat polycystic ovarian syndrome (PCOS) complications like acnes, excessive hair growth and irregular periods. If you take Krimson correctly without missing any pills, then there is no chance of getting pregnant as Krimson prevents any wanted pregnancy. Krimson itself acts as a contraceptive, no need to take any other medication like I Pill for it. Don t stop Krimson in between let the pack gets over. Oral birth control pills like I Pill should not be taken while using Krimson. Because, side effects may be increased if you take Krimson with blood control pills like I Pill. Possible side effects are prolonged uterine bleeding, irregular menstrual periods, spotting between periods, mood swings, agitation, depression, breast tenderness and enlargement, fatigue, headache, weakness, blood clots, tiredness, nervousness, suicidal tendency, vaginal dryness, allergic reactions etc. Take care. Hope I have answered your questions. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General And Family Physician