Hand holding a diaphragm

Diaphragms and cervical caps are cups made of silicone.

It is put at the top of the vagina, to cover the cervix (neck of the womb).

It's used with spermicide (a cream that kills sperm), and necessary to check it's in the right place before sex.



  • Most people can use a diaphragm or cap
  • They are hormone-free
  • They can be put in up to 3 hours before sex
  • They offer some protection against STIs
  • Can have sex more than once with a diaphragm or cap in place (with extra spermicide)
  • Skin-skin contact


  • Diaphragms and caps are less effective than other methods
  • Technique needs a bit of practice
  • Needs to be put in before sex
  • They need to be left in 6 hours after sex
  • The spermicide can be messy
  • Some spermicides can increase the risk of HIV transmission

It’s not one size fits all

There are different varieties and sizes of caps and diaphragms.  A trained doctor or nurse can teach how to use it, and check that it's the right size. 

If it is felt by your partner during sex, it may mean a different size is needed. 

If a diaphragm is uncomfortable, it's probably not the right size

Good to know

Diaphragms and caps have no hormones.

You need to check whether the diaphragm is in the right place in the vagina - this is usually easy to learn.

How much effort are diaphragms and caps?

Caps and diaphragms can be obtained from clinics, or bought online. They are available in different sizes and it's important to get one which covers the cervix and sits comfortably inside. Find out more about where to get a diaphragm here

You need to learn how to check whether the diaphragm is in the right place (feeling for the cervix with a finger in the vagina). 

Diaphragms and caps need to be cleaned after use with soap and water, rinsed, and left to dry.  They should be checked for holes or signs of damage before use. 

You may need to change diaphragm size after gaining or losing weight, or having a pregnancy. 

They need to be put in before sex and left in for at least 6 hours afterwards. 

How effective are diaphragms and caps?

When used perfectly, diaphragms and caps are about 94% effective – meaning that if 100 people used a diaphragm or cap for a year, about 6 of them will have an unplanned pregnancy.  However, allowing for the ups and downs of life, the average user can expect them to be around 88% effective – meaning that if 100 people used a diaphragm or cap every day for a year, about 12 of them will have an unplanned pregnancy. 

How do they work?

The diaphragm and the cervical cap covers the cervix (neck of the womb), and are used with a spermicide cream which kills sperm.  

It must be left in for at least 6 hours after having sex, to allow time for the spermicide to work.