Diaphragms and caps
Key points about diaphragms and caps
- A diaphragm or cap is a type of contraception.
- It's a circular dome made of soft, stretchy silicone that you put into your vagina with spermicide to stop sperm from getting from your vagina into your cervix.
- Diaphragms and caps can be hard to use correctly and have a high rate of unintended pregnancies. Because of this, they're no longer available or recommended in Aotearoa New Zealand.
A diaphragm or cap is a type of contraception. It's a circular dome made of soft, stretchy silicone that you put into your vagina, with spermicide, to cover your cervix. It's designed to stop sperm from getting from your vagina into your cervix.
Diaphragms and caps are similar but caps are slightly smaller and can be left in place longer than diaphragms.
The diaphragm is typically only 84% effective at preventing pregnancy. Other more effective forms of contraception are recommended in Aotearoa New Zealand, read more about the different types of contraception.
If you have a diaphragm or cap that is in good condition, you can keep using it. It should last for 1 to 2 years. You will have to buy spermicide online and have it sent to Aotearoa New Zealand.
Before having sex, you coat and fill the cap or diaphragm with spermicide foam or gel, and insert it into your vagina. You will need to use more spermicide if you have sex again within 6 hours.
Possible side effects and disadvantages of the diaphragm and cap include:
- skin irritation
- a greater chance of bladder infection with the diaphragm (but not with the cap)
- no protection against sexually transmitted infections (STI) and possibly a greater chance of HIV infection.
Find out more about how to check the fit of your diaphragm(external link).
Diaphragms(external link) Sexual Wellbeing Aotearoa, NZ
Choosing your contraception(external link) Sexual Wellbeing Aotearoa, NZ
Brochures
A compact guide to sexual health(external link) HealthEd, NZ, 2010
Contraception – your choice chart(external link) Sexual Wellbeing Aotearoa, NZ, 2024
References
- What are diaphragms or caps?(external link) NHS, UK, 2024
- Diaphragms(external link) Sexual Wellbeing Aotearoa, NZ
Diaphragms are no longer recommended
Diaphragms and vaginal rings are no longer available on prescription in Aotearoa New Zealand. They are not recommended as a method of contraception as they are not easily available, can be difficult to use correctly and have a high rate of unintended pregnancies.
Contraception – which option for which patient?(external link) BPAC, NZ, 2021
Pericoital (on demand) contraception – diaphragm, cervical cap, spermicide and sponge(external link) UpToDate, US, 2024
New Zealand Aotearoa’s guidance on contraception(external link) Ministry of Health, NZ, 2020
Contraception(external link) BMJ Best Practice, UK, 2025
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Credits: Healthify editorial team. Healthify is brought to you by Health Navigator Charitable Trust.
Reviewed by: Lisa Harris, Registered Nurse Prescriber in primary health
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