Smart Girls, Safe Choices
Birth Control

The birth control shot

One injection every 3 months. No daily pill to remember, no device to insert. Here's everything you need to know about how it works and what to expect.

Effectiveness
99%
with perfect use; 96% typical use
How often
Every 3 months
must be on schedule to stay protected
Hormones
Progestin only
no estrogen — good for some people
STD protection
None
use condoms too

How the shot works

The birth control shot (brand name Depo-Provera) contains a synthetic progestin hormone called depot medroxyprogesterone acetate (DMPA). It's injected into your arm or buttock by a healthcare provider every 11–13 weeks.

1

Stops ovulation

The progestin prevents your ovaries from releasing an egg. No egg, no pregnancy.

2

Thickens cervical mucus

Makes it much harder for sperm to travel through the cervix toward an egg.

3

Thins the uterine lining

Makes the uterus less receptive to implantation as an additional backup mechanism.

Getting the shot: the schedule

Timing matters. Here's how the injection schedule works and what to do if you're late.

1

First shot

Can be given at any point in your cycle. If given within the first 7 days of your period, you're protected immediately. Otherwise, use a backup method (like condoms) for 7 days.

2

Repeat shots

Every 11–13 weeks (roughly every 3 months). Your provider will usually schedule your next appointment before you leave.

3

If you're late

If it's been more than 13 weeks since your last shot, you may need a pregnancy test before getting the next one. Use backup contraception until you've had the shot and 7 days have passed.

4

Where it's given

A clinic, doctor's office, or Planned Parenthood. Some areas offer self-injection options — ask your provider.

Side effects: what to expect

The shot is safe and effective, but it does come with side effects that are worth knowing about before you start.

Heads up: irregular bleeding is very common

This is the most common reason people stop using the shot. In the first 3–6 months, you may have unpredictable spotting, longer periods, or more frequent bleeding. After 12 months of use, about 50% of people stop having periods altogether — which is safe and normal. If unpredictable bleeding would be really disruptive for you, it's worth factoring that in.

Side effectWhenNotes
Irregular bleeding or spottingFirst 3–6 monthsVery common; usually improves over time. Many people eventually stop having periods.
Heavier or longer periodsEarly monthsCan happen initially before bleeding patterns settle.
No period at allAfter 12+ monthsHappens in about 50% of users. Safe and normal — not a sign of pregnancy.
Weight changesOngoingSome people gain a small amount of weight; others don't notice any change.
Mood changes or low moodOngoingSome people report mood shifts. If you have a history of depression, discuss this with your provider.
Headaches or nauseaEarly onUsually mild and temporary.
Decreased bone densityWith long-term useThe shot can reduce bone density over time. This is usually reversible after stopping. Not recommended for use beyond 2 years unless other methods aren't suitable — discuss with your provider.
Delayed return to fertilityAfter stoppingIt can take 6–18 months for your cycle to return to normal after stopping the shot. Not the best choice if you want to get pregnant soon.

Pros & cons

The honest breakdown to help you decide if the shot is right for you.

Pros

  • Only 4 injections per year — nothing to remember daily
  • Very effective at preventing pregnancy (99% with perfect use)
  • No estrogen — suitable for people who can't use estrogen-containing methods
  • Can reduce or eliminate periods over time
  • May help with endometriosis pain and heavy periods
  • Private — nothing to store at home or carry around
  • Works even if you have trouble swallowing pills

Cons

  • Irregular bleeding, especially in the first few months
  • Must visit a clinic every 3 months — no skipping appointments
  • Can't stop it immediately if you have side effects — lasts 3 months
  • Delayed return to fertility after stopping (6–18 months)
  • May reduce bone density with long-term use
  • No protection against STDs — still need condoms
  • Possible weight gain or mood changes for some people

Getting the shot confidentially

In most US states, minors can consent to contraceptive services without a parent's permission. Planned Parenthood and Title X-funded clinics offer confidential care on a sliding-scale fee. If you're on a parent's insurance, ask the clinic about paying out-of-pocket to avoid an Explanation of Benefits (EOB) being sent home.

Find a confidential clinic near you

Common questions

Real answers, no judgment.

Compare all methods

See how the shot stacks up against the pill, IUD, implant, and more — side by side.

Birth control overview

Find confidential care

Planned Parenthood and Title X clinics can prescribe the shot confidentially, often on a sliding-scale fee.

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