Contraceptive Injection

The birth control shot is a very effective and safe contraception. Each injection lasts eight or twelve weeks, depending on the injection die.

On this page

  • What is the birth control shot?
  • How does the birth control shot?
  • How effective is the birth control shot?
  • What are the advantages of the birth control shot?
  • What are the disadvantages of the contraceptive injection?
  • Are there any side effects with the birth control shot?
  • Who can not get the birth control shot?
  • How the contraceptive injection given?
  • Learn more
  • References

The contraceptive injection contains the hormone progestin. It has been used since the 1960s and is used worldwide. Depo-Provera ® is the brand used most often and is given every 12 weeks. Noristerat ® is a brand and is administered every 8 weeks.

The progestogen is injected into a muscle and then gradually released into the bloodstream. It works mainly by preventing the release of the egg from the ovary (ovulation). It also thickens the cervical mucus by which forms a mucus plug. This prevents sperm from reaching the uterus to fertilize an egg. It also makes thinner coating of the uterus. This makes it unlikely that a fertilized egg can implant in the uterus.

It is very effective. Less than 4 in 1,000 women become pregnant using it after two years. Compare this with contraception when not in use. More than 80 of every 100 sexually active women who do not use contraception become pregnant within a year.

  • You do not have to remember to take a pill every day. Just think about contraception every 2-3 months.
  • Does not interfere with sex.
  • Can be used when breastfeeding.
  • It may help some of the problems of the period, such as premenstrual tension, heavy periods and pain.
  • Can be used by some women who can not take the combined pill.
  • You can help protect against pelvic infection. The mucus plug in the cervix may stop bacteria from traveling into the uterus.
  • The injection can not be removed once given. Side effects will last for more than 2-3 months, until your body is progesterone.
  • As the injection duration is long, it takes some time after the last injection to become fertile again. It varies from woman to woman. Some women do not ovulate for 6-8 months after the last injection. In rare cases, it can take up to two years before the return of fertility. This delay is not related to the length of time using this method of contraception.
  • Your periods may change. During the first few months, some women have irregular bleeding can be heavier and longer than usual. However, it is rare for heavy periods persist. After the first few months, it is more common for periods become lighter than usual, but may be irregular. Many women have no periods at all. The longer you use, the more likely it will stop periods. Periods stop by around 7 in 10 women after having the injection for a year.

Some women find that having irregular or unpredictable periods can be a nuisance. However, if you develop irregular bleeding while receiving the injection, then you should inform your doctor. Irregular bleeding may sometimes be due to other reasons, such as infection. This may need to be treated.

Apart from the change in the period, side effects are rare. If one or more should occur, often set in a couple of months or so. Examples of possible side effects include weight gain, fluid retention, increased acne and breast tenderness.

The most common reason for women to stop having the injections is due to irregular bleeding.

The injection may cause a weakening of the bones. This does not usually cause any problems and bone will return to normal when the injections are stopped. The use of injectable contraceptives for many years, will further bone thinning. Therefore, it is recommended that you have a review every two years with your doctor or nurse. They will discuss whether this method is still the best for you.

Very occasionally, the injection may cause some pain or swelling at the site of injection. You should consult your doctor or nurse if you have any signs or symptoms of infection at the injection site (eg, redness or swelling).

Most women can get the birth control shot. Your doctor or family planning nurse to discuss any current and past disease. For example, you should have if you have recently had breast cancer or have hepatitis.

If you have risk factors for osteoporosis (thinning of the bones), then it is usually advisable to use another method of contraception. Examples of risk factors include not having a period of six months or more (as a result of excessive exercise, extreme dieting or eating disorders), alcohol abuse or a close family history of osteoporosis.

The injection is given into a muscle, usually in the buttock. Should not be administered during pregnancy. It is therefore important to ensure that you are not pregnant when you have your first injection.

For this reason, the first injection is given during the first 1-5 days of a period. If you have the shot within five days of the beginning of a period, you will be protected immediately. Subsequent injections then given up to 12 weeks apart, depending on the type used. If you can not make an appointment within that window of 5 days, you can have the injection at any time, as long as you are reasonably certain she is not pregnant. Your nurse or doctor will advise you to use an additional contraceptive method (such as condoms) for 7 days after injection. This is what is called an "off-label" and not all practices permit.

The doctor or nurse will tell what kind of shot you have and how long it is until the next injection. It can manage up to two weeks before. This can be useful if, for example, plans to be at a party at the next injection is due.

Note: you will lose the protection against pregnancy if you are late in having the next injection.

Your doctor, nurse and pharmacist are good sources of information if you have questions.

The FPA (formerly the Family Planning Association) also provides information and advice.
FPA Helpline: 0845 310 1334 or visit their website