Unlike the combined pill, which contains copies of the natural hormones oestrogen and progesterone, the progestogen only pill only uses a copy of progesterone.

When you digest the pill, the progestogen gets absorbed into your blood and changes your hormone levels. This affects your body and prevents pregnancy in 3 ways:

  • it thickens the mucus in the cervix to stop sperm from getting into the womb 

  • it stops ovulation in 60-97% of people, depending on which type you take

  • it thins the lining of the womb, so a fertilised egg can’t stay in place – this is a back-up measure as the eggs aren’t likely to be fertilised in the first place if you’re taking this pill

What happens to the progestogen only pill in your body?

  1. The pill is digested in your stomach.

  2. Your bloodstream takes the ingredients of the pill all over your body, changing your hormone levels and leading to other health benefits, risks and side effects.

  3. Your liver changes the hormones from the pill so they’re ready to be expelled from your body.

  4. Hormones are lost from your body through your bowel – so you have to keep taking them every day to keep hormones at the levels that prevent pregnancy.

What type of pill should you take?

There are several types of pill to choose from, and they all work the same way. But because of the type of progestogen they contain, different pills may suit different people. The 2 types of progestogen are called desogestrel and levonorgestrel.

Pills that contain desogestrel

Pros: it’s over 99% effective. It’s more likely to stop ovulation and you have 12 hours to remember to take it before it counts as a missed pill.

Brand names:

  • Cerelle

  • Cerazette

  • Zelleta

  • Feanolla

Pills that contain levonorgestrel

Pros: it’s highly effective at preventing pregnancy at 98.5%.

Cons: it’s less likely to stop ovulation and you only have a 3-hour window to remember to take it before it counts as a missed pill.

Brand names:

  • Norgeston

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