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Diaphragms and caps are barrier methods of contraception. They fit inside your vagina and prevent sperm from passing through the entrance of your womb (the cervix).
Diaphragms are soft, thin domes made of latex (rubber) or silicone. Caps are smaller and are also made of latex or silicone. They come in different shapes and sizes.
To be effective in preventing pregnancy, they need to be used in combination with spermicide, which is a chemical that kills sperm.
You only have to use a diaphragm or cap when you have sex, but you must leave it in for at least six hours after the last time you had sex. You can leave it in for longer than this, but do not take it out before.
Read more about how to use diaphragms and caps.
If used correctly and in combination with spermicide, diaphragms and caps are estimated to be 92%-96% effective in preventing pregnancy. This means that if 100 women use a diaphragm or cap, between four and eight of them will become pregnant in one year.
There are other more effective contraceptives available, such as the oral contraceptive pill. Some women prefer to use diaphragms or caps because they do not like taking the pill. Others can't take the pill for health reasons.
Diaphragms and caps only provide limited protection against sexually transmitted infections (STIs). If you're at a high risk of getting an STI – for example, you or your partner has more than one sexual partner – you may be advised to use another form of contraception.
Read more about things to consider before using diaphragms and caps.
You can get a diaphragm or cap from:
The cervix is at the lower end of the womb. It connects the womb with the vagina.
Most women are able to use diaphragms and caps. However, they may not be suitable for you:
Diaphragms and caps can provide only limited protection against STIs. Research shows that some spermicides, which contain the chemical nonoxinal-9, do not protect against STIs and may even increase your risk of getting an STI.
A diaphragm or cap will be less effective if:
If any of these things happen, or you have had sex without contraception, you may need to take emergency contraception.
You can use a diaphragm or cap after having a baby but you may need a different size. It is recommended that you wait at least six weeks after giving birth before using a diaphragm or cap.
You can use a diaphragm or cap after a miscarriage or abortion, but you may need a different size.
When you first start using a diaphragm or cap, a doctor or nurse will examine you and advise on the correct size or shape to suit you.
They will show you how to put in and take out a diaphragm or cap, and also how to use the spermicide, which must be applied every time you use a diaphragm or cap.
Your doctor or nurse will show you how to put in a diaphragm. Diaphragms come with instructions and are all inserted in a similar way.
You can insert a diaphragm up to three hours before you have sex. After this time you will need to take it out and put some more spermicide on it.
Your doctor or nurse will show you how to put in a cap. Caps come with instructions and are all inserted in a similar way.
You can insert a cap up to three hours before you have sex. After this time you will need to take it out and put some more spermicide on it.
You may be fitted with a temporary diaphragm or cap by your doctor or nurse. This is for you to practise with at home. It gives you the chance to learn how to use it properly, see how it feels and find out if the method is suitable for you.
During this time you are not protected against pregnancy and need to use additional contraception when you have sex.
When you go back for a follow-up appointment with your doctor or nurse, wear the diaphragm or cap so they can check that it is the right size and you have put it in properly.
When they are happy that you can use a diaphragm or cap properly, they will give you one to use as contraception.
A diaphragm or cap can be easily removed by gently hooking your finger under its rim, loop or strap and pulling it downwards and out.
You must leave all types of diaphragm and cap in place for at least six hours after the last time you had sex.
You can leave them in for longer than this, but do not leave them in for longer than the recommended time. For latex types this is 30 hours (including the minimum six). For the silicone cap it is 48 hours (including the minimum six).
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.