Each Cerazette (Desogestrel)tablet contains 75 microgram desogestrel. The tablet is white, round, biconvex and 5 mm in diameter. On one side it is coded KV above 2 and on the reverse side Organon. Tablets must be taken every day at about the same time so that the interval between two tablets always is 24 hours. The first tablet should be taken on the first day of menstrual bleeding. Thereafter one tablet each day is to be taken continuously, without taking any notice on possible bleeding. A new blister is started directly the day after the previous one.

The most commonly reported undesirable effect in the clinical trials is bleeding irregularity. Some kind of bleeding irregularity has been reported in up to 50% of women using Cerazette. Since Cerazette causes ovulation inhibition close to 100%, in contrast to other progestogen-only pills, irregular bleeding is more common than with other progestogen-only pills. In 20 - 30% of the women, bleeding may become more frequent, whereas in another 20% bleeding may become less frequent or totally absent. Vaginal bleeding may also be of longer duration. After a couple of months of treatment, bleedings tend to become less frequent. Information, counselling and a bleeding diary can improve the woman's acceptance of the bleeding pattern. The most commonly reported other undesirable effects in the clinical trials with Cerazette > 2.5%) were acne, mood changes, breast pain, nausea and weight increase. The undesirable effects mentioned in the table below have been judged, by the investigators, as having an established, probable or possible link to the treatment.