Contraceptive injections

Contraception is a way for men and women to prevent pregnancy. There are many different methods of contraception; some types also protect against sexually transmitted infections (STIs). The contraceptive injections Depo-Provera and Noristerat do not protect against STIs.

Depo-Provera and Noristerat are contraceptives for women. They are made up of a hormone similar to progesterone and are given as an injection by a doctor or nurse into a muscle in the woman's arm or buttock. Each Depo-Provera injection provides protection against pregnancy for up to 12 weeks, and each Noristerat injection is effective for up to eight weeks. The injections must be received on time for the woman to remain fully protected.

How soon do the injections work?

Contraception with Depo-Provera and Noristerat begin immediately after the first injection if given within the first five days of your menstrual period.

How effective are the injections?

Both Noristerat and Depo-Provera are 99% effective in preventing pregnancy. However, they do not prevent the spread of STIs. To help protect yourself from STIs, use a male condom each time you and your partner have sex if either one of you could have an STI.

Can any woman use the injections?

Most women can use Depo-Provera, however, it may not be recommended for women who have:

• Unexplained vaginal bleeding
• Liver disease
• Breast cancer
• History of heart disease or stroke
• Diabetes with complications
• Risk factors for osteoporosis

Noristerat is only used for short periods of time in most women and usually women are only ever given one or two injections. The times a woman can use Noristerat include if she is waiting for the results from her partner’s vasectomy, has just had a rubella vaccine or wants immediate contraception after the birth of a baby or termination of a pregnancy.

Noristerat is not recommended for women who are having surgery within 12 weeks and may not be recommended for women who have:

• Diabetes
• Breast or endometrial cancers
• Liver tumours
• Depression
• High blood pressure
• Blood clots

Are there side effects associated with the injections?

Depo-Provera can cause a number of side effects, including:

• Irregular menstrual periods, or no periods at all
• Headaches
• Nervousness
• Depression
• Dizziness
• Acne
• Changes in appetite
• Weight gain
• Excessive growth of facial and body hair
• Hair loss
• Loss of bone mineral density

The side effects from Noristerat include:

• Breast discomfort
• Headaches
• Depression or the return of depression
• Dizziness
• Nausea
• Reaction at the injection site

Most of the side effects are not common. Change in the menstrual cycle is the most common side effect. You may experience irregular bleeding or spotting. Since the Noristerat injection is only given once or twice, most side effects will stop after the second injection.

However, with Depo-Provera, after a year of use, about 50% of women will stop getting their periods. Their periods usually return when they discontinue the injections.

Prolonged use of Depo-Provera may result in significant loss of bone mineral density, increasing the risk of osteoporosis. This risk is more likely for those who have been taking it for longer than two years, particularly when other risk factors for osteoporosis exist, such as family history of osteoporosis and long-term alcohol and/or tobacco use. Although there are no studies to show benefit, it is advised that all women on Depo-Provera get adequate calcium and vitamin D (through diet and/or supplements) to help prevent osteoporosis.