Diaphragms and caps are round dome-shaped devices made from thin, soft silicone. You put them into your vagina before you have sex. 

Used correctly, they can help prevent pregnancy, but they are not quite as effective as other types of contraception, such as the pill.

Around 4 to 8 women in 100 who use a diaphragm or cap correctly for contraception may get pregnant in any 1 year. 

A diaphragm or cap is a barrier method of contraception. It should be used with a spermicide gel that kills sperm. 

The diaphragm or cap sits inside your vagina and stops sperm going through the cervix (the entrance to your womb). You can put it in any time before you have sex, but you will need to apply extra spermicide if you leave it in for 3 hours or more before having sex. 

Your doctor or nurse can show you how to use it.

You must leave your diaphragm or cap in for at least 6 hours after you have sex. 

Most women can use a diaphragm or cap, but they can be hard to get used to. Your doctor or nurse might give you one to test out before you decide. 

They can be a good choice if you cannot use hormonal contraception or do not want to. They are a good option if you only want to use contraception when you have sex, rather than using a longer-term method.

A diaphragm or cap may not be right if you: 

  • have an unusually shaped cervix
  • have weakened vaginal muscles 
  • have an allergy to latex or spermicide
  • have ever had toxic shock syndrome (TSS) 
  • get frequent urinary tract infections (UTIs)
  • have a vaginal infection 
  • are at higher risk of getting a sexually transmitted infection (STI)

Pros: 

  • There is no need to take hormones or chemicals.
  • They have no major health risks or side effects. 
  • You can usually use the same one for a year before you need a new one. 
  • You only need to think about using it when you have sex. 

Cons:

  • They are not as good as other types of contraception at preventing pregnancy.
  • Your cap or diaphragm may not fit if you put on or lose more than 3kg, or if you have a baby, a miscarriage, or an abortion.
  • They do not protect against STIs, so you may need to use a condom as well. 
  • They can trigger bladder infections in some women.
  • Latex and spermicide can be irritants for you or your partner.
  • You cannot use them while you’re on your period. There is a risk this could cause toxic shock syndrome, a rare but life-threatening illness.  
  • They need to be washed and stored with care between each use. 

You can get a cap or diaphragm from some sexual health clinics, contraception clinics and GP surgeries.  
 
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