Contraceptive injection1
What is it?
The contraceptive injection contains the hormone progestogen and is a long-term method of contraception, which lasts for 8 or 12 weeks depending on the type. The injection is administered in your upper arm or buttocks.
How does it work?
The contraceptive injection works in the same way as the combined pill by:
- Stopping the ovaries from releasing an ovum
- Thickening the mucus of the cervix to act as a barrier to sperm
- Stopping a fertilised ovum from settling by keeping the lining of the womb thin
How effective is it?
The contraceptive injection is over 99% effective.
What are the benefits?
- Injectable progestogen can be used by women who cannot take oestrogen
- No need to remember to take everyday and doesn’t interrupt sex
- Provides contraception for up to 8 or 12 weeks (depending on type used)
- Can be used by breastfeeding women
- Not affected by any medications
Are there side effects?
- Your fertility and periods can take a while to get back to normal with some contraceptive injections
- As the injection cannot be removed, any side effects will last as long as the injection
- Irregular periods can continue for some months after stopping the injections
- Can increase the chance of spots, headaches and tender breasts
- Weight gain, mood swings and bloating
- Periods may stop
- Injections have been shown to have a slight effect on bone density
- Fertility can take up to 1 year to return after injections have stopped
You should not use the contraceptive injection if you are/have had any of the following:
- You might be pregnant
- You don’t want any changes to your periods
- You have cancer of the breast or breast cancer in the last five years
- Have had a heart attack or stroke
- Unexplained bleeding from the vagina
- Have active liver or gall bladder disease
- Severe depression
What are the drawbacks?
- You must regularly make appointments to renew the injections
What do I do if I want to become pregnant?
If you want to try for a baby, inform your doctor or nurse that you will not be needing your next injection. Your periods and fertility may take a while to return after you stop using the injection. It is advisable to wait for one natural period before trying to get pregnant. This means the pregnancy can be dated more accurately and you can start pre-pregnancy care such as folic acid and stopping smoking.
1. fpa. Sex/sexual health – contraception – the contraceptive injection
