Hi, Welcome to HCM! I understand your doubt. This medication is used in women to prevent pregnancy after birth control failure (e.g., broken condom) or unprotected sex. It is a progestin hormone that prevents pregnancy by preventing the release of an egg (ovulation) and changing the womb and cervical mucus to make it more difficult for an egg to meet sperm (fertilization) or attach to the wall of the womb (implantation). Some common side effects include nausea/vomiting, abdominal pain, tiredness, dizziness, changes in vaginal bleeding, breast tenderness, diarrhea, or headache may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any of the following symptoms of a serious allergic reaction: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. Hope this information helps. Feel free to ask if you have any doubt. Regards, Dr. Sridhar