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.
How effective are 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.
Where can I get a diaphragm or cap?
You can get a diaphragm or cap from:
- contraception clinics
- young people's services
- your doctor
- sexual health clinics (GUM clinics)
The cervix is at the lower end of the womb. It connects the womb with the vagina.
Who can use it
Most women are able to use diaphragms and caps. However, they may not be suitable for you:
- if you have an unusually shaped or positioned cervix (entrance to the womb), or if you cannot reach your cervix
- if you have weakened vaginal muscles (possibly as a result of giving birth) that cannot hold a diaphragm or cap in place
- if you have a sensitivity or an allergy to latex or the chemicals in spermicide
- if you have ever had toxic shock syndrome (a rare but life-threatening bacterial infection)
- if you have repeated urinary tract infections (an infection of the urinary system, such as the urethra, bladder or kidneys)
- if you currently have a vaginal infection (wait until your infection clears before using a diaphragm or cap)
- if you are not comfortable touching your vagina
- If you have a high risk of getting a sexually transmitted infection (STI), for example, if you have multiple sexual partners
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:
- It is damaged – for example, it is torn or has holes.
- It is not the right size.
- You use it without spermicide.
- You do not use extra spermicide with your 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 things happen, or you have had sex without contraception, you may need to take emergency contraception.
After having a baby
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.
After a miscarriage or abortion
You can use a diaphragm or cap after a miscarriage or abortion, but you may need a different size.
How does it work
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.
Inserting a diaphragm
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.
- With clean hands, put a small amount of spermicide on each side of the diaphragm. Also putting a little spermicide on the rim may make 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, then try again.
- Some women squat while they put their diaphragm in. Others lie down or stand with one foot up on a chair. Use the position that's easiest for you.
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.
Inserting a cap
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.
- Fill one-third of the cap with spermicide, but do not put any spermicide around the rim as this will stop the cap 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. Slide the cap into your vagina upwards and backwards. The cap must fit neatly over your cervix. It stays in place by suction.
- Depending on the type of cap, you may need to add extra spermicide after it has been put in.
- Some women squat while they put their cap in. Others lie down or stand with one foot up on a chair. Use the position that's easiest for you.
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.
Practice diaphragm or cap
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.
Removing a diaphragm or cap
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).
Looking after your diaphragm or cap
- After use, you can wash your diaphragm or cap with warm water and mild unperfumed soap. Rinse it thoroughly, then leave it to dry. You will be given a small container for it, which you should keep in a cool, dry place.
- Never boil a diaphragm or cap. Do not use disinfectant, detergent, oil-based products or talcum powder to keep it clean, as these products can damage it.
- Your diaphragm or cap may become discoloured over time but this does not make it less effective. Always check your diaphragm or cap for any signs of damage before using it.
- You can visit your doctor 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 diaphragm or cap if you gain or lose more than 3kg (7lb) in weight, or if you have a baby, miscarriage or abortion.