Contraception - injections

Hormonal contraception comes in several forms, one of which is a slow-release injection. The contraceptive injection delivers the hormone progestogen, which is similar to a hormone produced by the ovaries. It is often known by the brand name Depo.

Different methods of contraception may suit you at different stages of your life. When you are choosing the method that best suits you, it can help to talk to a doctor or nurse about your options.

Other types of hormonal contraception include:

• the contraceptive implant
• the hormonal IUD
• oral tablets (the combined pill and the progestogen-only, or mini, pill)
• the vaginal ring

How the contraceptive injection works#

The injection works by preventing the ovaries from releasing an egg each month. It also thickens the fluid around the cervix (the opening to the uterus or womb), which helps to prevent sperm from reaching an egg.

When it is first given, or after a break, the injection can take up to 7 days to start working to prevent pregnancy. Keep using condoms for another 7 days after that first injection.

How to use it#

A doctor or nurse injects the progestogen into the muscle tissue in your arm or buttock. For continued contraceptive protection, this should be repeated every 12 to 14 weeks. Its effectiveness is reduced if the injection is delayed.

It can be helpful to write down the date or set a reminder in your phone for when your next injection is due.

Effectiveness#

Each injection is more than 99% effective at preventing pregnancy when used the right way.

Advantages#

• it is very effective
• most users have no vaginal bleeding at all, or very light bleeding
• periods may be less painful
• it lasts for 12 to 14 weeks
• it can be used while breastfeeding
• no medications stop it from working
• it is another choice if you have difficulty taking the hormone estrogen, because the injection only contains progestogen (the combined pill and the vaginal ring contain estrogen)

Side effects#

Your menstrual bleeding pattern will change. It might become more frequent or irregular. Around 50 to 60% of women will have no bleeding at all, which is not harmful to the body. Episodes of prolonged or frequent bleeding may improve with time, and some medications can help with this bleeding, so speak to your doctor or nurse.

Around 20% of users will gain weight. There is a small drop in bone density (your bones become thinner). This is not thought to be harmful, as bone density returns once you stop the injections.

Other possible side effects for a small number of users can include:

• headaches
• bloating
• changes to your skin
• sore or tender breasts
• mood changes

These side effects often settle with time.

Serious health problems#

There are no known serious health risks from having the contraceptive injection.

Who it may not suit#

The contraceptive injection might not be a good option if you:

• have plans to become pregnant soon
• have been treated for breast cancer
• have severe liver disease
• have risk factors for heart disease (such as smoking or diabetes)
• have previously had a heart attack or a stroke

If you are late having the injection#

Depo might not work if the next injection is delayed beyond the recommended time. Once it is more than 14 weeks since your last injection, use condoms until you can have your next injection.

If you get pregnant while using the injection#

The injection is not known to harm a pregnancy. It is safe to continue the pregnancy (and stop having the injections) or to have an abortion.

After having a baby#

Depo can be given straight after you give birth, whether or not you are breastfeeding. However, other types of contraception might be a better choice until the baby is 6 weeks old, because it may cause heavy or irregular bleeding. Talk to your doctor about which contraceptive choice is most suitable for you at this time.

Becoming pregnant again#

The effects of the contraceptive injection can take some months to wear off, so it might take a while to become pregnant after you stop.

Protection from infections#

The contraceptive injection does not protect you from sexually transmissible infections (STIs). Condoms provide the best available protection from STIs.

The contraceptive injection is one of many types of contraception. Many community health services and some public hospitals have family planning, sexual health or women’s health clinics that provide contraception and can help you compare your options.

Key points#

• The injection works by preventing the ovaries from releasing an egg each month.
• It also thickens the fluid around the cervix, which helps to prevent sperm from reaching the egg.
• When first given, or after a break, it can take up to 7 days to start working to prevent pregnancy.
• There are no known serious health risks from having the contraceptive injection.

Where to get help#