What is the injectable contraceptive?
The injectable contraceptive (or “the shot”) is an injection that is given in the arm or buttocks 4 times per year (every 12-13 weeks). It contains only one hormone (a progestin) and does not contain estrogen. The shot contains a 90-day dose (150 milligrams) of the progestin hormone medroxyprogesterone.
Because the injectable contraceptive is administered once every 3 months, some women may find it convenient to include it as part of their quarterly routine. Incorrect use of any hormonal contraceptive is associated with an increased risk of unintended pregnancy.
How does it work?
Progestin inhibits ovulation and thickens the cervical mucus, making it difficult for sperm to reach the egg.
Common questions about the shot:
Can I administer the shot myself?
No, the shot is administered by your healthcare professional every 3 months.
Will I gain weight taking the shot?
Some women receiving the shot will experience weight gain, but a significant percentage will not. Dietary counselling is advised.
Factors to consider about the injectable contraceptive
- It provides reliable contraception for up to 3 months
- When initiated later in the menstrual cycle, it may not be effective for 3 or 4 weeks, so use an extra method of birth control (barrier method) such as condoms or spermicides
- If you are planning to become pregnant, it may take several months (up to 9 months) before you start to ovulate and resume normal menstrual cycles
- It reduces the risk of endometrial cancer (a non-contraceptive benefit)
- It has been associated with loss of bone mineral density, which may not be completely reversible
- It does not protect against sexually transmitted infections (STIs)
Factors to consider about progestin-only contraceptives
- They are effective and reversible
- They may have slightly different side effects than combined hormonal contraceptives because they do not contain estrogen
- They may decrease menstrual bleeding and cramping
- They can be used by women who are sensitive to estrogen-containing contraceptives
- They can be used by breastfeeding mothers and have no effect on breast milk production
- Progestin-only contraceptives do not protect against sexually transmitted infections (STIs)
- Common side effects associated with progestin-only contraceptives include: headaches, nausea, breast tenderness, dizziness, and bleeding irregularities
Inform yourself and talk to your doctor
There are many choices of hormonal contraceptive available. Do your own research and speak with your doctor about the advantages and disadvantages of the different available types of hormonal contraceptive and choose the one that best fits your needs.
For tips on how to get the most out of your doctor’s visit, see Talking to your doctor.
Cigarette smoking increases the risk of serious adverse effects on the heart and blood vessels. This risk increases with age and becomes significant in hormonal contraceptive users over 35 years of age. Women who use hormonal contraceptives are strongly advised not to smoke.
