Injectable contraceptives are injected into the muscle of the buttocks or the upper arm. The hormones are then released slowly from the muscle into the bloodstream and carried to the target organs.

There are two types of contraceptive injection: those that are used monthly (once-a-month injection) and those that are injected every 3 months (3-month injection). The once-a-month injection contains an estrogen and a progestin, the longer-acting three-month injection only a progestin.

Action and effectiveness

The injectable contraceptives are very reliable. The monthly injection almost always suppresses ovulation. With the 3-month injection ovulation is usually only suppressed in the first 4 to 8 weeks. But even after that you still have contraceptive protection as the 3-month injection suppresses the build-up of the uterine lining and makes the cervical mucus impenetrable for sperm.

The contraceptive injection does not provide protection against HIV or other sexually transmitted diseases.

If you want to have sex with a partner you know little about you should also use a condom.

Advantages

The contraceptive injection is suitable for women who want long-term contraception. As progestin-only preparation the 3-month injection is particularly suitable for women who have problems with estrogens.

You don't have to think about contraception for a month or three months, depending on the type of injection used. This gives you plenty of room for spontaneity in your love life. Women who have difficulty taking the pill regularly also benefit from the contraceptive injection because they no longer have to remember to take a pill every day.

When you stop having the injections you can become pregnant again.

The 3-month injection is also suitable for women who are breast-feeding. Although hormonal contraceptives are not the method of choice for these women, progestin-only preparations can be used. Only very small amounts of the progestin are secreted into the breast milk. We know from experience that this does not harm the child.

Your doctor will tell you when you can start using the 3-month injection.

The intrauterine system and the minipill are also suitable methods of hormonal contraception after giving birth.

Side-effects and risks of the contraceptive injection

The contraceptive injection is a potent drug which can also have unwanted side-effects. The following information gives a general outline of the side-effects and risks of the contraceptive injection. However, in case of conflicting information the product information of the preparation you have been prescribed always takes precedence. It is therefore important to read the pack insert carefully and follow any advice given by your doctor.

As with all hormonal contraceptives you may initially experience mild side-effects such as nausea, headaches or breast tenderness. However, these symptoms usually disappear after a short time.

Skin reactions at the injection site may occur.

The main disadvantage of the 3-month injection is that there are often bleeding abnormalities, particularly in the first few weeks. After longer use of the 3-month injection periods may stop altogether as administration of a progestin alone causes marked suppression of the build-up of the uterine lining. However, this is no cause for concern.

The once-a-month injection allows somewhat better control of the bleeding pattern. The side-effects of the monthly injection are comparable to those of other combined hormonal contraceptives. Further information may be found in the section 'Side-effects and risks of the combined oral contraceptive'.

When you stop the injections your fertility returns to the previous level. However, with the contraceptive injection this sometimes takes a little longer than with the intrauterine system or the pill.

Who should not use the contraceptive injection?

There are medical conditions and circumstances, so-called contraindications, in which use of the 3-month injection is not allowed or not advisable.

There are also cases in which the once-a-month injection should not be used.

Injections are not the hormonal method of choice for adolescents. Although there are no age-specific contraindications the combined oral contraceptive is preferable as injectable contraceptives more often lead to bleeding abnormalities and menstruation often stops completely when they are used for a prolonged period of time. Even after stopping the contraceptive injection it can be several months before a normal cycle pattern is restored.

The combined oral contraceptive, on the other hand, regulates the menstrual cycle. After stopping the pill normal cycles with regular periods resume immediately.