First the Facts

  • Vaginal diaphragms and cervical caps are both types of barrier contraception that fit inside the vagina.
  • The physical barrier prevents pregnancy by stopping sperm from entering the womb and meeting an egg (barrier method).
  • They do not contain any hormones, and they do not prevent sexually transmitted infections (STIs). In order to protect against STIs, additional condom use is required.
  • Diaphragms and caps are similar, but they fit inside the vagina slightly differently. Diaphragms cover the cervix (neck of the womb) and the area around it, whereas caps fit more tightly on to the cervix itself. They have similar efficacy (effectiveness in preventing pregnancy) and therefore choosing between these options is a matter of personal preference.
  • Diaphragms and caps are inserted before having vaginal sex and stay in situ for a minimum of six hours after sex, but no more than 24–48 hours (depending on the specific type). They both need to be used in conjunction with a spermicide.
  • A new generation diaphragm called Caya® is now available, and this comes in one size only.

How Do They Work?

  • By covering the neck of the womb during and after sex, diaphragms and caps prevent sperm from reaching an egg, so that the egg cannot be fertilised.
  • Both diaphragms and caps need to be used in conjunction with a spermicide, which is a gel or cream that kills sperm, making it less likely for sperm to pass into the womb and out to the fallopian tube where fertilisation would take place.
  • It is important to leave the diaphragm or cap in place for at least six hours after sex because sperm may remain in the vagina for several hours after sex. If left in the vagina, the acid environment kills sperm, preventing fertilization.
  • When used ‘perfectly’ (as directed), along with using spermicide, diaphragms and caps are between 92 and 96% effective at preventing pregnancy. This means that out of 100 people having sex using diaphragms or caps for a year, between 4 and 8 people will become pregnant. With typical use (taking into account human error) they are between 71 and 88% effective, which means that between 12 and 29 people will become pregnant in a year.

Vaginal diaphragm for birth control

How Do I Use the Diaphragm or Cap?

  • Before inserting the diaphragm or cap, it can be useful to feel for your own cervix by inserting a clean finger into the vagina. The cervix is a firm, round structure that is located at the top of the vagina.
  • It is important to remember to use spermicide when inserting a diaphragm or cap. If having sex multiple times, more spermicide should be inserted into the vagina at two-hourly intervals.
  • Diaphragms and caps should be inserted before having sex.
  • Inserting diaphragms and caps can be made easier by squatting or resting one foot on a chair or something similar. Diaphragms and caps should be left in situ for at least six hours after having sex. They can be left in situ for up to 48 hours after sex – different manufacturers have different maximum durations for which they can be left in place.

Inserting a Diaphragm

  • Put plenty of spermicide on the upper part of the diaphragm and around the edge to help it slip in
  • Fold the diaphragm using your fingers and insert into the vagina and let it open up
  • Make sure it is covering the cervix

Inserting a Cap

  • The cap should fit closely around the cervix
  • Fill the cap with spermicidal gel or cream (one third of the cap)
  • Squeeze the cap using your fingers and insert it into the vagina
  • Push it over your cervix until firmly in place
  • The cap stays in position by suction

Removing Diaphragms and Caps

  • Make sure the diaphragm or cap has been left in place for at least six hours after having sex
  • Do not leave it in for longer than recommended by the manufacturer
  • Use a clean finger to gently pull the outer rim of the diaphragm or cap downwards

If you are still unsure how to insert or remove the diaphragm or cap, seek advice from a healthcare professional.

How Long Can Diaphragms and Caps Be Used for?

  • Diaphragms and caps are reusable. After removal, they should be cleaned with warm water and unperfumed soap before being used again
  • As long as there are no tears in the diaphragm or cap, they can be used for many years
  • A different size may be required if you have recently been pregnant, or if your weight has changed significantly

Are There Any Side Effects?

  • There are no medical side effects related to the use of diaphragms or caps
  • There is a possibility of an allergy to a component of the device or the spermicide – check with your healthcare professional before considering the method

Special Considerations

  • Anybody who has a vagina and cervix can use diaphragms and caps. They do not contain hormones, and therefore there are very few contraindications.
  • The diaphragm or cap may not be suitable for some of the following reasons:
    • Current infection in the vagina
    • Suffered from toxic shock syndrome in the past
    • Frequent urine infections
    • Cervix that is in a difficult position to reach
    • Not comfortable with the process of inserting the diaphragm or cap
    • Diaphragm or cap will not stay in place
    • Anatomical variations, e.g. very short vagina (diaphragm), duplex system with two cervices (cap)

Where Can I Get a Diaphragm or Cap?

You can get a diaphragm or cap free from:

  • A sexual health, genitourinary medicine or contraception clinic
  • A young person’s clinic
  • Some GP surgeries

You will need to be assessed by a healthcare professional to make sure you get the correct size for you as everyone has different anatomy.

You may also be able to get Caya® from a pharmacy – online or in store –, but it is still important to be examined first to ensure that Caya® is right for you.

Is the Cap or Diaphragm Right for Me?

There are advantages and disadvantages of using diaphragms and caps for contraception:

Effective at preventing pregnancy if used correctly Difficult to use whilst bleeding
No hormonal side effects No protection against sexually transmitted infections
Safe for most people to useMay need a different size after pregnancy or change in weight
ReusableDifficulty with insertion and removal
Irritation from spermicide

Are Diaphragms and Caps Safe to Use Whilst on a Period?

  • Diaphragms and caps should not be used whilst on a period. This is because they cover the cervix and stop the menstrual blood from emptying into the vagina. This means that blood can build up and could cause an infection such as toxic shock syndrome.

Do Diaphragms and Caps Work after Being Pregnant?

  • Yes, diaphragms and caps still work after pregnancy.
  • People who have recently given birth may start using diaphragms or caps from six weeks after the birth. However, they may need to use a different size to previously.
  • When having sex before six weeks, a different form of contraception should be used.
  • Diaphragms and caps can also be used after a miscarriage, ectopic pregnancy or termination of pregnancy. In these situations, there is no need to wait for six weeks, although the size of the diaphragm or cap may need to be changed.

Can Lubrication (Lube) Be Used with Diaphragms, Caps, and Spermicide?

  • Yes, lube can be used together with a diaphragm or cap. However, it is important that the lube is water-based and not oil- or silicone-based. This is because oil- or silicone-based lube can damage the diaphragm or cap, making it less effective.

Will the Diaphragm or Cap Stay in Place Whilst Having a Shower or Bath?

  • Baths can cause diaphragms and caps to move from the correct position; therefore, it is better to have a shower instead of a bath whilst the diaphragm or cap is in place.


Written by: Ela Owen, Dr Nikki Kersey and Dr Paula Briggs
Last updated: January 2021

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