Diaphragm or Cap

What are they?

  • Soft, flexible latex or silicone dome/cup shaped devices that fit in the vagina and cover the cervix (entrance to the womb). Caps are usually smaller.
  • They should be used with a spermicide.

How do they work?

  • Act as a barrier preventing sperm from entering the womb thereby stopping fertilisation with an egg.
  • The spermicide kills the sperm.

What’s great about them?

  • Quite effective – up to 6 out of 100 women will become pregnant each year if they are used perfectly and consistently. If not used perfectly more women will become pregnant (12 in 100)
  • You can insert the diaphragm ahead of time (up to three hours before sex) so that it doesn't interrupt sex.
  • Contains no hormones so no side effects and your period is not affected.
  • You only have to use it when you have sex.

What’s not so great about them?

  • Can “interrupt the mood” during sex if it’s not put in beforehand.
  • You should leave it in for at least 6 hours after the last time you had sex.
  • Extra spermicide is needed if you have sex again.
  • Spermicide can be messy.
  • They are less effective than most methods but better than using nothing. They fail because: device is damaged e.g. torn/has hole; wrong size; doesn’t cover the cervix; spermicide not used consistently; device is removed too soon; use of oilbased lubricants which damage the latex.
  • No protection against sexually transmitted infections (STIs) – condoms advised.
  • If your body changes in certain ways, you might need a different size diaphragm.
  • The diaphragm cannot be used when you have your period.
  • The latex or spermicide can cause irritation of the penis or vagina and cystitis.
  • Can take time to learn how to use it.

Where can I get it?

  • Sexual Health services.
  • Family planning clinics
  • Some GP practices

Sexual Health London offers a free STI testing across most of London.
Simply register for SHL and complete an online consultation to order your free STI test kit.