Yaz is a low dose combined oral contraceptive pill and is used as an effective means of birth control to prevent unwanted pregnancy. Yaz contraceptive pills contain a combination of two hormones at low doses in a single pill. Each pack of Yaz contains one month’s supply of pills (28 days) of which there are 24 hormone-containing pills and 4 placebo (non-hormonal) pills, to allow each monthly cycle to end with a withdrawal bleed. When using Yaz for contraception, you will probably find that your periods become regular and you may also experience lighter, less painful menstruation and an improvement in pre-menstrual symptoms, like bloating, swelling or weight gain related to fluid retention, also improvement in acne and reductions in greasiness of the skin and hair.