Diaphragms and caps

Diaphragms and caps are barrier methods of contraception. They fit inside your vagina and cover your cervix (entrance to the uterus – womb).

They come in different shapes and sizes. Vaginal diaphragms are circular domes made of thin, soft latex (rubber) or silicone with a flexible rim. Cervical caps are smaller and are made of latex or silicone.

To be effective, diaphragms and caps should be used with a spermicide. Spermicides are chemicals that kill sperm.

Your Guide to Diaphragms and Caps (PDF)

How effective any contraceptive is depends on how old you are, how often you have sex and whether you follow the instructions.

If 100 sexually active women don’t use any contraception, 80 to 90 will become pregnant in a year. If used according to instructions, diaphragms and caps are 92–96 per cent effective when used with spermicide. This means that between four and eight women in 100 will get pregnant in a year.

If diaphragms and caps are not used according to instructions, more women will get pregnant.

A diaphragm or cap stops sperm reaching an egg. It covers your cervix while the spermicide kills any sperm. To be effective in preventing a pregnancy, it is recommended that you use spermicide with a diaphragm or cap.

A diaphragm or cap will be less effective if:

  • it is damaged, for example if it is torn or has holes in it
  • it doesn't cover your cervix
  • it isn't the right size
  • you use it without spermicide
  • you have sex three hours or more after you put it in and you don't use extra spermicide
  • you don't use extra spermicide with you diaphragm or cap every time you have more sex
  • you remove it too soon (less than six hours after the last time you had sex)
  • you use oil-based products such as baby lotion, bath oils or some vaginal medicines (for example, pessaries) with latex diaphragms or caps. These can damage the latex.

If any of these happen, or if you have had sex without using contraception, you can get advice about emergency contraception.

  • You only have to use it when you have sex.
  • It has no serious health risks.
  • You are in control of your contraception.
  • You can put it in before you have sex. You will have to add extra spermicide if sex takes place more than three hours after putting it in.
  • Some people find the spermicide messy.
  • It can take time to learn how to use it.
  • Some people are sensitive to the chemicals in latex or spermicide. This may cause irritation in some women or a partner.

Most women can use a diaphragm or cap. A diaphragm or cap may not be suitable if you:

  • have vaginal muscles which can't hold a diaphragm in place
  • have a cervix which is an unusual shape, in an awkward position or if you cannot reach it
  • are sensitive to the chemicals in latex or spermicide
  • have repeated urinary infections
  • have a vaginal infection (wait until after the infection has cleared)
  • have ever had toxic shock syndrome
  • do not feel comfortable touching your vagina.

If you have a high risk of getting a sexually transmitted infection, for example if you or your partner has more than one partner, it may be advisable not to use a diaphragm or cap. Research shows that spermicide which contains Nonoxinol 9 does not protect against sexually transmitted infections. It may even increase the risk of getting a sexually transmitted infection.

You may need a different size diaphragm or cap after you have had a baby. It is advisable to wait until at least six weeks after having a baby before using a diaphragm or cap.

Yes you can, although you may need a different size diaphragm or cap after a miscarriage or abortion.

You can get a diaphragm or cap from contraception clinics and young people's services, and some general practices and genitourinary medicine (GUM) clinics.

Diaphragms come with instructions and a doctor or nurse will show you how to put it in. The different types of diaphragm are all used in a similar way.

With clean hands, put a small amount of spermicide on the upper surface of the diaphragm (approximately two 2cm strips). Some women find that putting a little spermicide on the rim makes the diaphragm easier to put in.

Put your index finger on top of the diaphragm and squeeze it between your thumb and other fingers. Slide the diaphragm into your vagina upwards and backwards. This should ensure that the diaphragm covers your cervix.

Always check that your cervix is covered. It feels like the end of your nose. If your cervix is not covered, take the diaphragm out by hooking your finger under the rim or loop (if there is one) and pulling downwards and try again.

Some women squat while they put their diaphragm in. Others lie down or stand with one foot up on a chair. You will need to find out which position is easiest for you.

Caps come with instructions and a doctor or nurse will show you how to put it in. The different types of cap are all used in a similar way.

Fill one-third of the cap with spermicide, but don’t put any spermicide around the rim as this will stop the cap from staying in place. The silicone cap has a groove between the dome and the rim; some spermicide should also be placed there.

Squeeze the sides of the cap together and hold it between your thumb and first two fingers. The cap must fit neatly over your cervix. It stays in place by suction. Always check that your cervix is covered. Depending on the type of cap, you may need to add extra spermicide after it has been put in.

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 it for longer, but don’t leave a diaphragm or cap in for more than the recommended time. For latex types this is 30 hours, including the minimum six hours and for the silicone cap, 48 hours including the minimum six.

Take it out by gently hooking your finger under the rim, loop or strap and pulling downwards.

When you take your diaphragm or cap out, wash it in warm water with a mild, unperfumed soap. Then rinse it thoroughly. Dry it carefully and keep it in its container in a cool, dry place.

Never boil your diaphragm or cap, never use disinfectant or detergent to clean it or use talcum powder with it. Do not use any oil-based product with latex types as it will damage them.

Before use, check your diaphragm or cap regularly for tears or holes by holding it up to the light and having a good look at it. Be careful with your fingernails and jewellery. If your diaphragm goes out of shape, squeeze it gently back into its circular shape.

Your diaphragm or cap may become discoloured. But don’t worry, this will not make it less effective.

It is not recommended that you use a diaphragm or cap during your period because of a possible risk of toxic shock syndrome.

Put your diaphragm or cap in after a bath rather than before. Water may dislodge it or wash away the spermicide. Have a shower rather than a bath during the six hours after you have had sex when you need to keep your diaphragm or cap in.

The effect of swimming or water sports has not been studied, but it is likely to be small.

A doctor or nurse will sometimes fit you with a practice diaphragm or cap. Practice diaphragms and caps give you time and privacy to find out if the method is suitable for you and to learn how to use it properly. While you are learning to use it, don’t rely on it to stop you getting pregnant. You will need to use an additional method of contraception if you have sex.

During this time try putting the diaphragm or cap in and check that it covers your cervix. You can have sex with the diaphragm or cap in place and leave it in for a few hours to find out if it is comfortable for you and a partner. It is also a good idea to use the spermicide to see how this feels.

When you go back to get it checked, wear the diaphragm or cap so the doctor or nurse can check that you have put it in properly and that it is the right size.

Once you have a diaphragm or cap that you are happy with, you only need to see a doctor or nurse to replace it or if you have any questions or concerns. You may need a different size diaphragm or cap if you gain or lose more than 3kg (7lb) in weight or if you have recently had a pregnancy.

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This website can only give you general information about contraception. The information is based on evidence-guided research from the World Health Organization and The Faculty of Sexual and Reproductive Healthcare of the Royal College of Obstetricians and Gynaecologists. All methods of contraception come with a Patient Information Leaflet which provides detailed information about the method.

Remember – contact your doctor, practice nurse or a sexual health clinic if you are worried or unsure about anything.

INFORMATION LAST UPDATED JANUARY 2014. NEXT UPDATE DUE 2015.