The Shot

What is the birth control shot?

  • The birth control shot (the shot) is taken by someone with ovaries inside their body to prevent pregnancy.
  • The shot is taken by injection (a needle), usually in the hip area, at a health care provider’s office.
  • It contains artificial hormones similar to the natural hormones that already exist in the body.

How does the shot work?

  • The shot stops the ovaries from releasing an egg cell each month. If there is no egg cell, pregnancy is not possible.
  • The pill makes the cervical mucus thicker so that it is harder for sperm to get into the cervix.
  • It also makes the lining of the uterus thinner, so it is harder for a fertilized egg cell to stick to the uterus. Even if an egg cell is released and fertilized, if it is unable to implant into the uterine lining a pregnancy will not
  • When used correctly, the pill prevents pregnancy 99.7% of the time.

How often do I need to have the injection?

  • The injection is given once every three months.
  • Remember to have the injection on schedule.
  • If you are late for your injection, the birth control shot does not protect against pregnancy.
  • If you are having penis-vagina sex, consider another form of birth control such as condoms for 2 weeks after a late injection to make sure you are protected against pregnancy during this time.

How soon does it start working?

  • If you have the shot within the first five days of your menstrual cycle, it begins working 24 hours after the injection.
  • If you have the birth control injection after the first five days of your menstrual cycle, it begins working after 14 days.
  • When the birth control injection is given to a person immediately after they have given birth, had a miscarriage, or had an abortion, it works immediately.

Where can I get the shot?

You will need a prescription for the shot. You can get a prescription from:

  • Your health care provider
  • A Teen Clinic (for youth 21 or younger)
  • A walk-in clinic
  • A community health clinic

Does the shot protect me from STIs and HIV?

  • No, the shot is only for pregnancy prevention.
  • Use safer sex supplies such as condoms and sex dams every time you have sex to reduce the risk of STIs (sexually transmitted infection) or HIV.

Will the shot affect my period?

  • Some people have heavier periods or bleeding between periods.
  • Some people find that after a while on the shot their period may lessen or stop.
  • If you stop using the shot your period will return. For long-term users, this may take a few months.

Are there any side effects?

Yes, there is a possibility of side effects that include:

  • Breast discomfort
  • Increased appetite
  • Mood changes or depression. If this affects your mental wellbeing, talk with your health care provider about alternative options.
  • Headaches
  • Dizziness
  • Less interest in sex
  • Loss in bone density. This is more common for long-term users. Talk with your health care provider for more information. Bone density loss can contribute to the development of osteoporosis. Exercise, calcium, and not smoking help prevent osteoporosis in all people.

Unlike other forms of birth control, if you have side effects from the shot you must wait until the drug totally wears off. This can take a few months.

Where can I get more information?

  • From your health care provider, community health clinic, or public health nurse. If you need a regular health care provider, call the Family Doctor Finder at 204-786-7111.
  • From the Facts of Life Online: e-mail your questions to
  • From a Teen Clinic if you are 21 or younger.
  • Our youth website,

Sexuality Education Resource Centre 2021

To view or download a PDF version of this information, click here: The Shot 2021