The "traditional" progestogen-only pill (POP) prevents pregnancy by thickening the mucus in the cervix to stop sperm reaching an egg. The desogestrel progestogen-only pill can also stop ovulation. Progestogen-only pills contain the hormone progestogen, but don't contain oestrogen. You need to take the progestogen-only pill reliably every day.
At a glance: facts about the progestogen-only pill
- If taken correctly, it's more than 99% effective. This means fewer than 1 woman in 100 who uses the progestogen-only pill as contraception will get pregnant in 1 year.
- With "typical use" of the progestogen-only pill (the way it's taken by a lot of women in real life), it's only about 92% effective.
- You take a pill every day, with no break between packs of pills.
- The progestogen-only pill can be used by women who can't use contraception that contains oestrogen.
- You can take the progestogen-only pill if you're over 35 and you smoke.
- You must take the progestogen-only pill at the same time each day. If you take it more than 3 hours late (traditional progestogen-only pill) – or 12 hours late (desogestrel pill) – it may not be effective.
- If you're sick (vomit) or have severe diarrhoea, the progestogen-only pill may not work.
- Some medicines may affect the progestogen-only pill's effectiveness – ask your doctor for details.
- Your periods may stop or become lighter, irregular or more frequent.
- Side effects may include spotty skin and breast tenderness – these should clear up within a few months.
- You'll need to use condoms as well as the progestogen-only pill to be protected against sexually transmitted infections (STIs).