A diaphragm or cervical cap is a small bowl-shaped dome made out of silicone or latex. It stops sperm reaching an egg by covering the cervix. It fits inside the vagina.
Diaphragms and caps are always used with spermicide, a chemical gel or foam that kills sperm. You can put your diaphragm or cap in, with spermicide up to 3 hours before you have sex. It must be left in place for at least 6 hours after sex.
How effective is this method?
When fitted correctly and used with spermicide, the diaphragm is 92-96% effective in preventing pregnancy.
Advantages of diaphragms and cervical caps:
- They don't interrupt sex because they can be put in before. You'll have to add extra spermicide if sex takes place more than 3 hours after putting it in.
- There are no health risks associated with them.
- They contain no hormones.
- They're available in both latex and non-latex, so they're still an option if you have a latex allergy.
- Some research suggests that using the diaphragm may give some protection against cervical cancer and some sexually transmitted infections (STIs) because the diaphragm or cap covers and protects key body parts at risk of infection.
Disadvantages of diaphragms and cervical caps:
- It can take a while to learn how to fit them correctly.
- Some people find the spermicide is messy, or irritates their skin.
- Using the diaphragm may, very rarely, cause cystitis.
- They’re not as effective in preventing pregnancy as most other types of contraception.
Things to bear in mind
If you gain or lose weight your diaphragm may not fit properly and will be less effective. If your weight changes, it’s important to see a doctor or nurse to get a new diaphragm.
Most importantly, the diaphragm and cap do not provide any protection against HIV – although they may protect against some other STIs.
Where can I get it from and how much does it cost?
The diaphragm is available free on the NHS. You can only get it on prescription. This can be from your GP, sexual health clinic, a practice nurse or young person's clinic.