Hi, Thanks for posting your query. I am happy to address your questions, Cycloreg contains norethisterone, it is used as a birth control pill to prevent pregnancy. It can also be used to treat other menstrual disorders such as excessive bleeding during periods and premenstrual syndrome (PMS). When you first start Norethisterone, you may experience irregular periods, spotting or prolonged bleeding. This is normal and should get better with time as you continue to take the medicine. However, if you miss your period for 45 days or more, or if your periods last much longer than usual, alert your doctor immediately. Norethisterone may also cause breast tenderness, stomach problems, rash, acne, headache, mood changes, changes in sexual drive, tiredness, as well as changes in weight and appetite. It may also cause dizziness. Alert your doctor if any of these side effects are severe or refuse to go away. Hope I have answered your query. If you have any further questions, I will be happy to help. Thanks