Birth control shot design

The birth control shot: Everything you need to know

The Depo-Provera birth control shot is a hormone injection with progestin that helps prevent pregnancy. Since 1992, it’s been a convenient form of birth control that doesn’t require taking a pill every day.

How the shot works

Like the mini-pill but longer-lasting, the shot contains progestin. This hormone thickens cervical mucus making it harder for the sperm to enter the uterus. It also suppresses ovulation (egg release) and thins the uterine lining (making it harder for a fertilized egg to implant). The Depo shot does not impact your ability to become pregnant in the future.

How often you need to do something

You’ll need to get the shot once every three months to maintain effectiveness for preventing pregnancy. 

Benefits and drawbacks

The shot might be the right birth control option for you. Here are all the points to consider. 


  • Only need to take it once every three months
  • Slightly more effective at preventing pregnancy than the pill (when used regularly)
  • Protects you from pregnancy immediately or within one week depending on when you get your first shot
  • Half of people on the shot don’t get their periods anymore (which is perfectly safe)
  • Doesn’t interfere with sex
  • Doesn’t require partner participation


  • After your last shot, it may take up to a year to become pregnant (may not be a fit for those looking for a temporary or short-term contraceptive) 
  • Possible side effects include irregular periods, weight gain, breast tenderness, headaches, depression, change in sex drive, nausea, and mood changes; many report that these side effects decrease 2-3 months into treatment.
  • Usually needs to be administered by a health care provider, although sometimes you can do the injections at home
  • More likely to cause weight gain than birth control pills and IUDs
  • Possible bone density loss 
  • Doesn’t protect against STIs 


The shot is 99% effective in preventing pregnancy if you get it once every three months (every 12 weeks). Chances of pregnancy increase if you delay your shot. You can start the shot anytime. You’ll be protected from pregnancy after one week, or right away if you get your shot within the first seven days of your period starting. If you are late getting your next dose, you should let your provider know. They can advise you about whether or not you can take a dose of emergency contraception (plan B) or if you need to wait and take a pregnancy test before getting your next dose.

Where and how to get it 

You need a prescription for the shot. It’s usually given by a health care provider or family planning clinic, although sometimes you can get a home supply to do injections yourself. 

Average cost

A single injection that lasts for three months costs between $0 and $150 including the medical exam, but many health insurance plans and government health plans cover the expense.

Who’s eligible

Most healthy premenopausal women are candidates for the shot, and it’s a great fit for those who have a tough time taking a pill at the same time every day. Talk with your healthcare provider to see if the shot will work for you. You may not be eligible if you’ve had blood clots, heart problems, certain types of cancers, bone fragility, liver disease, unexplained vaginal bleeding, or other health conditions.

Want to learn about other types of birth control? Check out these posts.

Reviewed by the Clinical Health Team

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