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The diaphragm is sometimes also known as the cap.

It is:

  • 92-96% effective when you use the method correctly every time
  • 71-88% when you don’t always use the method correctly

What is it?

It is a barrier method that a woman fits inside her vagina.

How does it work?

The diaphragm covers the woman’s cervix (neck of womb), and this stops a man’s sperm from reaching her egg.

You can use spermicide to cover the diaphragm. This will help it work better.


  • You can put the diaphragm in place any time before you have sex (extra spermicide may be needed).
  • You can re-use the diaphragm after careful washing with water.
  • It is useful for women who wish to avoid hormones.


  • You need to have a check-up at least once a year to make sure it still fits.
  • You have to use spermicide every time you have sex.
  • You must leave the diaphragm in place for at least six hours after sex, but must not leave it in for more than 24 hours.
  • Some users suffer from cystitis (a swollen bladder which means you find it painful to pee).
  • It does not protect against sexually transmitted infections.

For more information, please visit your GP or your family planning clinic.