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Your contraception guide

Contraceptive diaphragm or cap

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A contraceptive diaphragm or cap is a circular dome made of thin, soft silicone that's inserted into the vagina before sex.

It covers the cervix so sperm can't get into the womb (uterus) to fertilise an egg.

contraceptive cap

At a glance: contraceptive diaphragm or cap

  • When used correctly with spermicide, a diaphragm or cap is 92-96% effective at preventing pregnancy – this means that between 4 and 8 women out of every 100 who use a diaphragm or cap as contraception will become pregnant within a year.
  • There are no serious health risks.
  • You only have to think about it when you have sex.
  • You can put in a diaphragm or cap with spermicide any time before you have sex.
  • More spermicide is needed if it's been in place for more than 3 hours.
  • The diaphragm or cap needs to be left in place for at least 6 hours after sex.
  • It can take time to learn how to use it.
  • Some women develop cystitis (a bladder infection) when they use a diaphragm or cap. Your doctor or nurse can check the size – switching to a smaller size may help.
  • If you lose or gain more than 3kg (7lbs) in weight, or have a baby, miscarriage or abortion, you may need to be fitted with a new diaphragm or cap.
  • By using condoms as well as a diaphragm or cap, you'll help to protect yourself against sexually transmitted infections (STIs).

How the contraceptive diaphragm or cap works

A diaphragm or cap is a barrier method of contraception. It fits inside your vagina and prevents sperm passing through the cervix (the entrance of your womb). You need to use it with a gel that kills sperm (spermicide).

You only have to use a diaphragm or cap when you have sex, but you must leave it in for at least 6 hours after the last time you had sex. You can leave it in for longer than this, but don't take it out before.

You need to apply more spermicide if:

  • you have sex again with the diaphragm or cap in place
  • the diaphragm or cap has been in place for 3 hours or more before you have sex

Don't take the diaphragm or cap out to reapply spermicide.

When you first start using a diaphragm or cap, a doctor or nurse will examine you and advise on the correct size.

A diaphragm or cap doesn't provide reliable 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. 

You shouldn't use a diaphragm or cap during your period as there is a possible link with toxic shock syndrome (TSS), a rare condition that can be life threatening.

Inserting a diaphragm or cap

Your doctor or nurse will show you how to put in a diaphragm or cap.   

Some women squat while they put their diaphragm or cap in; others lie down or stand with one foot up on a chair – use the position that's easiest for you.

Inserting a diaphragm

  • with clean hands, put two 2cm strips of spermicide on the upper side of the diaphragm
  • 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 – this should ensure that the diaphragm covers your cervix
  • always check that your cervix is covered – it feels like a lump, a bit like the end of your nose
  • if your cervix isn't covered, take the diaphragm out by hooking your finger under the rim or loop (if there is one) and pulling downwards, then try again

Inserting a cap

  • with clean hands, fill one-third of the cap with spermicide, but don't put any spermicide around the rim as this will stop the cap staying in place
  • the cap has a groove between the dome and the rim – place some spermicide in this groove
  • squeeze the sides of the cap together and hold it between your thumb and first two fingers
  • slide the cap into your vagina, upwards
  • the cap must fit neatly over your cervix – it stays in place by suction
  • depending on your type of cap, you may need to add extra spermicide after it's been put in

Your doctor or nurse may give you a temporary diaphragm or cap to practise with at home. You can learn how to use it properly and find out if the method is suitable for you. 

During this time, you're not protected against pregnancy and need to use additional contraception, such as condoms, when you have sex.

When you go back to see your doctor or nurse, wear the diaphragm or cap so they can check it's the right size and you've put it in properly. When they're happy that you can use it properly, they'll give you one to use as contraception.

Removing a diaphragm or cap

Hook your finger under its rim, loop or strap and gently pull it downwards and out. You must leave your diaphragm or cap in place for at least 6hours after the last time you had sex.

You can leave them in for longer than this, but don't leave them in for longer than the recommended time of 30 hours (including the minimum of 6 hours). 

Looking after your diaphragm or cap

After using, you can wash your diaphragm or cap with warm water and mild unperfumed soap. Rinse it thoroughly, then leave it to dry and put it in its container. Keep it in a cool, dry place.

  • Never boil a diaphragm or cap.
  • Don't use disinfectant, detergent, oil-based products or talcum powder, as these can damage it.
  • Use water-based or silicone-based lubricant rather than oil-based lubricant, if needed.
  • Your diaphragm or cap may become discoloured over time, but this doesn't make it less effective.
  • Always check your diaphragm or cap for any signs of damage before using it.

You can visit your GP or nurse when you want to replace your diaphragm or cap. Most women can use the same diaphragm or cap for a year before they need to replace it.

You may need to get a different size if you:

  • gain or lose more than 3kg (7lb) in weight
  • have a baby, miscarriage or abortion

You're advised to wait until 6 weeks after having a baby before using a diaphragm or cap.

Who can use a diaphragm or cap?

Most women are able to use a diaphragm or cap, but it may not be suitable for you if you: 

  • have an unusually shaped or positioned cervix (entrance to the womb), or if you can't reach your cervix 
  • have weakened vaginal muscles (possibly as a result of giving birth) that can't hold a diaphragm in place
  • have a sensitivity or an allergy to latex or the chemicals in spermicide 
  • have ever had toxic shock syndrome  
  • have repeated urinary tract infections  
  • currently have a vaginal infection (wait until your infection clears before using a diaphragm or cap) 
  • aren't comfortable touching your vagina 
  • have a high risk of getting an STI – for example, if you have multiple sexual partners

Research shows spermicides that contain the chemical nonoxynol-9 don't protect against STIs, and may even increase your risk of getting an infection.

A diaphragm or cap may be less effective if:

  • it's damaged – for example, it's torn or has holes 
  • it's not the right size for you
  • you use it without spermicide 
  • you don't use extra spermicide with your diaphragm or cap every time you have more sex 
  • you remove it too soon (less than 6 hours after the last time you had sex)
  • you use oil-based products, such as baby lotion, bath oils, moisturiser or some vaginal medicines (for example, pessaries) with latex diaphragms – these can damage the latex

If any of these things happen or you've had sex without contraception, you may need to use emergency contraception.

Advantages and disadvantages

Advantages of a diaphragm or cap:

  • you only need to use a diaphragm or cap when you want to have sex
  • you can put it in at a convenient time before having sex (use extra spermicide if you have it in for more than 3 hours)
  • there are usually no serious associated health risks or side effects
  • you're in control of your contraception

Disadvantages of a diaphragm or cap:

  • it's not as effective as other types of contraception, and it depends on you remembering to use it and using it correctly
  • it doesn't provide reliable protection against STIs
  • it can take time to learn how to use it
  • putting it in can interrupt sex
  • cystitis (bladder infection) can be a problem for some women who use a diaphragm or cap
  • latex and spermicide can cause irritation in some women and their sexual partners


There are no health risks associated with using a contraceptive diaphragm or cap if you use it according to the instructions that come with it.

Where you can get a diaphragm or cap

Contraception is free to all women and men through the NHS.

Places where you can get contraception include:

  • community contraception clinics 
  • some genitourinary (GUM) clinics
  • sexual health clinics – they also offer contraceptive and STI testing services
  • most GP surgeries
  • some young people's services (call the Sexual Health Line on 0300 123 7123 for more information)

Find your nearest sexual health clinic

Contraception services are free and confidential, including for people under the age of 16.

Find out about the different types of contraception in Which contraceptive method suits me?

If you're under 16

The doctor, nurse or pharmacists won't tell your parents (or carer) as long as they believe you fully understand the information you're given, and your decisions.

Doctors and nurses work under strict guidelines when dealing with people under 16. They'll encourage you to consider telling your parents, but they won't make you.

The only time a professional might want to tell someone else is if they believe you're at risk of harm, such as abuse. The risk would need to be serious, and they would usually discuss this with you first.

Page last reviewed: 30/01/2018
Next review due: 30/01/2021