The cervical cap is a vaginal barrier method of birth control. It consists of silicone rubber and works by preventing sperm from entering your uterus. To get one, you’ll need a prescription from a doctor.

Barrier methods to help prevent pregnancy, such as condoms or cervical caps, have been around for centuries. As the name suggests, the cervical cap covers the cervix, which prevents semen from entering the uterus. People have used a version of the cervical cap since the late 1800s.

The Food and Drug Administration (FDA) approved the modern cervical cap in 1988. Various brands are available, but FemCap is the only cervical cap currently available in the United States.

The cervical cap is a reusable dome-shaped cap made from nonallergenic silicone rubber that you insert into the vagina. It is a nonhormonal barrier method.

The cervical cap is similar to the diaphragm. The only difference is it’s slightly smaller and fits more tightly over the cervix.

The cervical cap stops sperm from entering the uterus and fallopian tubes. If sperm cannot enter the fallopian tubes to fertilize the egg, pregnancy can’t occur.

It’s important to use spermicide with the cervical cap for maximum effectiveness. Spermicide stops the sperm from moving and is a second line of defense against pregnancy.

You need a prescription to get a cervical cap.

To insert the cervical cap:

  1. Wash your hands.
  2. Apply spermicide in the dome of the cap and spread a thin layer on the rim of the cap.
  3. Put a small amount of spermicide in the folded area between the rim and the dome.
  4. Separate your labia with one hand.
  5. With the other hand, squeeze the brim of the cervical cap.
  6. Insert the cervical cap into your vagina, dome side down.
  7. Push the cap back toward the rectum and then up toward the cervix.
  8. Use your fingers to make sure the cervix is completely covered.

Before you have sex, make sure the cervical cap is still in place. If you have sex multiple times, you don’t need to remove the cap but you should insert more spermicide. It’s also advisable to make sure the cap is still in position.

The cervical cap must stay in place for at least 6 hours following intercourse. Don’t remove the cap before then. Doing so greatly lowers its effectiveness.

Keeping the cervical cap in place will give the spermicide time to kill any sperm before you uncover your cervix. But don’t leave the cap in for more than 48 hours as it can increase your risk of bacterial infection.

To remove the cap:

  1. Wash your hands with soap and water.
  2. Squat down, and insert your fingers into your vagina.
  3. Grip the removal cap and rotate the cap as you push the dome to release the suction.
  4. Pull the cap out.
  5. Wash the cap with soap and water.
  6. Let the cap air-dry.

How well the cervical cap works depends on two things: whether you use it according to the instructions and whether you’ve ever been pregnant.

According to Planned Parenthood, the failure rate for the cervical cap is 14% for women who have never given birth. This rate increases in women who have been pregnant. The failure rate increases to 29% in women who have had a vaginal birth.

You can make the cap more effective by always using it exactly as prescribed. It’s also important to regularly check your cap for small holes and any other damage and replace it immediately if necessary. Discoloration of the cap isn’t a problem.

Although it’s not the most effective form of birth control, the cervical cap is very convenient. Some benefits of the cap are that it:

  • can be inserted in advance without interrupting intimacy
  • can be used multiple times
  • is low cost
  • has no side effects from hormones

The cervical cap has a few disadvantages, including that it:

  • is not the most effective form of birth control
  • doesn’t protect against sexually transmitted infections (STIs)
  • is easy to use incorrectly
  • can slide, or be pushed out of place, during intercourse
  • can be uncomfortable for the woman or her sexual partner
  • can’t be used during menstruation
  • requires the use of spermicide, which may cause irritation to either partner

Most people find the cervical cap safe and easy to use. In rare cases, it can cause serious side effects. Talk with your doctor if you have any of the following symptoms:

  • burning during urination
  • pain while the cap is in place
  • blood inside the cap when you remove it
  • genital itching or irritation
  • redness or swelling
  • unusual or foul-smelling discharge

In addition, if you are at high risk for STIs you may want to consider another method of contraception. Most spermicides used with the cap contain nonoxynol-9 (N-9). N-9 can increase your susceptibility to HIV and other STIs. The risk is particularly high if you use N-9 multiple times per day.

The cervical cap is a prescription-only, nonhormonal method of birth control. It works by stopping sperm from entering the uterus.

It’s important to use the cap alongside spermicide for maximum effectiveness and keep it in place for at least 6 hours after intercourse. It’s 71% to 86% effective at preventing pregnancy. FemCap is the only cervical cap currently available in the United States.