Marvelon is a combined oral contraceptive pill that contains Desogestrel (0.15 mg) and Ethinylestradiol (0.03 mg). It is used primarily to prevent pregnancy. The medication works through three main mechanisms: inhibiting ovulation (preventing the release of eggs), thickening the cervical mucus to block sperm entry, and altering the uterine lining to prevent implantation. Marvelon is taken as one tablet daily for 21 consecutive days, followed by a 7-day break during which a withdrawal bleed occurs. The pill does not provide protection against sexually transmitted infections, so additional contraception methods like condoms are recommended for STI prevention.