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GB-NON-02457 | Date of Preparation: April 2020


Diaphragms and caps

A contraceptive diaphragm or cap is a circular dome made of thin, soft silicone that's inserted into the vagina before sex as a form of birth control.
It covers the cervix so sperm can't get into the uterus to fertilise the egg. For this reason they’re sometimes called a ‘barrier method’ of contraception. You need to use it together with a spermicide.1


Diaphragms and caps key facts

Diaphragms and caps are similar: diaphragms are circular domes with a flexible rim; caps are the same but smaller.2 They are available in different sizes and when you first start using one, your doctor or nurse can advise you on the correct size to use.1 They do not contain hormones.2


A diaphragm or cap is a small silicone dome2


They are only used when you have sex2


Diaphragms and caps are less effective than some other contraceptive methods1

  • The typical effectiveness is 71–88%,* or 92–96% when used perfectly and with spermicide3
  • You can put it in beforehand so you don’t have to interrupt sex. Add extra spermicide if sex takes place more than 3 hours after putting it in.2
  • Can be suitable if you don’t want long-term contraception and want to avoid hormones
  • Can take time to learn how to use diaphragms and caps1
  • Can be messy as it needs to be used with spermicide1
  • Needs planning before sex1

The pros and cons listed are not exhaustive. Talk to your doctor or nurse for more information.

*These are "typical" effectiveness rates, which is how effective the method is with an average person. Typical rates tend to reflect real life usage (including inconsistent and incorrect use). "Perfect" effectiveness rates are how effective the method is when used perfectly. Refer to the patient information leaflet for "perfect" use.

Common questions

Who are diaphragms and caps not suitable for?

If you’ve got an unusually-shaped cervix or weakened vaginal muscles, then you might have to rule this one out. Talk to your doctor or nurse about whether it’s right for you.1

How is the diaphragm and cap used in practice?

Before you have sex, you need to prepare. You put the spermicide1 on your diaphragm or cap and then put it into your vagina, until it covers your cervix. The way you do this varies and your doctor or nurse can show you a few ways. After sex, it needs to stay in for at least 6 hours. When you take it out, you should clean it and store it somewhere safe until the next time you need it.1

Similar contraceptive types

This contraceptive is a type known as spontaneous – for more contraceptives like this, click below



Tell me more

So what do I do now?

Now you have a few options for types of contraception that might be right for you, you should have a chat with a GP/doctor or nurse.


Sexual health clinic

Visit your local clinic for more information on the choices available to you.

Find out more


Pop into your local pharmacy and ask about your options.

Find a pharmacy

GP clinic

Make an appointment with your nurse or doctor so you can chat about what options are best for you.

Find a GP

You may want to download information on your options to help with your discussion.

Download now

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