The majority of women using hormonal contraception use low-dose preparations (containing 20-30 microg ethinyloestradiol). There are usually two types of combined oral contraceptives (COCs) on the market: - Monophasic pills, in which every pill contains the same amount of oestrogen and progestogen. Bi- or triphasic pills, in which every pill contains both oestrogen and progestogen but the amounts vary in different phases of the menstrual cycle. There is no significant difference in efficacy or adverse effects between monophasic and biphasic pills (evidence C). - Start with low dose products independent of the age of woman unless there is some contraindication.