Combined oral contraceptives are over 99% effective at preventing pregnancy when taken correctly. This means that fewer than 1 in 100 who use the combined pill as contraception will get pregnant in 1 year.

Progesterone only pills are also more than 99% effective, when taken correctly. However, in reality with ‘typical use’ (i.e., the way it’s taken by a lot of women in real life), this medication is around 91% effective in preventing pregnancy. The effectiveness of treatment may decrease if it is not taken around the same time each day. If the traditional progesterone-only pill is taken more than 3 hours late – the desogestrel (Cerazette) pill is taken more than 12 hours late – it may not be effective.

Although all of our content is written and reviewed by healthcare professionals, it should not be substituted for or used as medical advice. If you have any questions about your health, please speak to your doctor.

Authored Apr 22, 2021 by Joseph Issac, MPharm
Reviewed Jun 15, 2021 by Prabjeet Saundh, MPharm