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The contraceptive injection is a progestogen only hormone given into the muscle (usually the upper arm or buttock) every 12 weeks by a health professional. The hormone is slowly released into the body.
Depo Provera® and Depo Ralovera® are brand names of the contraceptive injection available in Australia.
The contraceptive injection works by:
- stopping the body from releasing an egg every month
- making the mucus in the cervix thicker, so sperm cannot get through
- changing the lining of the uterus
It is 94% effective at preventing pregnancy in typical use or 99.8% effective if it is used within the timeframe.
The contraceptive injection is suitable for those who:
- cannot take oestrogen
- have difficulty remembering to take daily contraception
- are taking regular medications that interfere with other types of hormonal contraception
- are breastfeeding.
The contraceptive injection is not suitable for those who:
- have had breast cancer within the last five years
- have severe liver disease
- have had severe depression, including postnatal depression
- have undiagnosed abnormal vaginal bleeding
- have had a heart attack or stroke
- have a high risk of osteoporosis.
The contraceptive injection can be given at any time that pregnancy can confidently be excluded.
The first contraceptive injection is effective immediately if it is given between day one (first day of bleeding) and day five of your menstrual cycle. If it is given at any other time of the cycle, back-up contraception (e.g. condoms) should be used for the next seven days.
Subsequent injections should be given every 12 weeks in order to maintain its effectiveness. It is safe to take up to two weeks early or two weeks late. If you are more than two weeks late, it is important that you use another form of contraception (e.g. condoms), until your next injection.
- Can cause light periods or no periods at all.
- Not affected by changes in body weight.
- Not affected by stomach upsets (vomiting or diarrhoea).
- Only the date of the next injection needs to be remembered. Make a note of this date and book your appointment in advance.
- Does not protect against sexually transmissible infections (STIs).
- Once the injection has been given, it has to wear off, meaning that any side effects may persist for several months.
- Irregular bleeding may occur for the first few injections. This is usually light bleeding and for a few days only. Prolonged heavy bleeding is uncommon.
- Some people experience side effects such as headaches or mood changes.
- Some people may experience a small amount of weight gain. This is higher in those who are already overweight.
- You may have slight loss of bone density while using this method. This appears to be regained after the method is stopped.
The return of fertility is often delayed by approximately six months on average, but the effect on fertility is temporary. Studies have shown no evidence of any effect on future pregnancies.
Those using the contraceptive injection may experience a loss of bone density, which may increase the risk of osteoporosis later in life.
To reduce the risk of osteoporosis, maintain a calcium-rich diet, do regular weight bearing exercise (low impact aerobics, weight training, walking or running) and avoid smoking.
The contraceptive injection does not protect against sexually transmissible infections (STIs).
Information last updated November 2019
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