The Short Answer
The birth control shot (Depo-Provera) is an injection of medroxyprogesterone acetate (a progestin) given every 12-13 weeks. It is 94% effective with typical use and 99.8% with perfect use. It is convenient (only 4 appointments per year), and most users eventually stop getting periods. The main downsides are potential weight gain, delayed fertility return after stopping, and temporary bone density loss with long-term use.
Key Points:
- One injection every 3 months, given at a clinic or self-administered (Depo-subQ)
- 94% typical effectiveness, 99.8% perfect
- Most users stop getting periods after 6-12 months
- Fertility return may take 6-12 months after stopping
- Linked to temporary bone density loss with extended use
How It Works
Depo-Provera delivers a high dose of medroxyprogesterone acetate (DMPA) that prevents ovulation for 12-14 weeks, thickens cervical mucus, and thins the uterine lining.
The injection is given in the arm (intramuscular) or thigh. A subcutaneous version (Depo-subQ Provera 104) can be self-administered at home.
Getting Your Shot
- First shot: Can be given any time. If started within the first 7 days of your period, it is effective immediately. Otherwise, use backup for 7 days.
- Follow-up shots: Due every 12-13 weeks. There is a 2-week grace period (up to 15 weeks from the last shot) before backup contraception is needed.
- At the visit: The injection itself takes seconds. The entire appointment is usually less than 15 minutes.
What to Expect
Months 1-3 (first shot): Irregular bleeding and spotting are common. Some users experience headaches, breast tenderness, or mood changes.
Months 3-6: Bleeding usually becomes less frequent. About 50% of users stop getting periods after 6 months.
After 1 year: About 70% of users have no periods. Side effects that were going to appear have usually shown up by now.
Side Effects in Detail
Bleeding changes: The most common side effect. Irregular spotting in the first 3-6 months, then periods usually become lighter or stop entirely. About 70% of users have no period after one year.
Weight gain: The shot is the birth control method most consistently associated with weight gain. Studies show an average gain of 5-8 lbs over 2 years, though individual results vary significantly.
Bone density: Long-term use (2+ years) is linked to a decrease in bone mineral density. This effect is partially reversible after stopping - most bone density returns within 2 years of the last injection. Your provider may recommend calcium (1,000 mg/day) and vitamin D supplements while on the shot.
Mood changes: Some users report mood swings, depressive symptoms, or anxiety. If you have a history of depression, discuss this with your provider before starting.
Headaches: Common in the first few months, usually temporary.
Fertility Return - The Key Difference
The shot is the only reversible method with a significant delay in fertility return. After your last injection:
- Average time to ovulation: 4-6 months
- Average time to pregnancy (for those trying): 9-10 months
- Some users: up to 18 months before fertility fully returns
This is not permanent - fertility does return. But if you are planning to get pregnant within the next year, the shot may not be your best choice.
Compare this to other methods' fertility return
Who Is the Shot Good For?
- You want a method that requires action only every 3 months
- You prefer not to have something inserted in your body
- You want your periods to stop (most users achieve this)
- You are breastfeeding (safe to use)
- You cannot use estrogen
- You are not planning pregnancy in the near future
Who Might Want to Consider Other Options?
- You want to get pregnant within the next 1-2 years
- You are concerned about weight gain
- You have osteoporosis risk factors (low bone density, family history, eating disorders, long-term steroid use)
- You have a history of depression that worsened on hormonal birth control
- You want a method you can stop at any time with immediate fertility return
The Shot vs Other Methods
| Factor | Shot | Combined Pill | Hormonal IUD | Implant |
|---|---|---|---|---|
| Action required | Every 3 months | Daily | None for years | None for years |
| Typical effectiveness | 94% | 91% | 99.8% | 99.95% |
| Fertility return | 6-12 months | Immediate | After removal | After removal |
| Periods | Usually stop | Lighter, regular | Lighter or absent | Unpredictable |
| Weight effect | Gain more likely | Minimal | Minimal | Minimal |
| Bone density | Temporary loss | No effect | No effect | No effect |
Frequently Asked Questions
Can I give myself the shot at home?
Yes, if your provider prescribes the subcutaneous version (Depo-subQ Provera 104). It is injected into the thigh or abdomen using a smaller needle than the clinic version.
What if I am late for my shot?
If you are less than 2 weeks late, get your shot as soon as possible - no backup needed. If more than 2 weeks late, get the shot and use backup contraception for 7 days after. More on missed doses.
Does the shot cause permanent infertility?
No. Fertility always returns. It just takes longer than other methods - typically 6-12 months after the last injection.
Can I switch from the shot to another method?
Yes. Your provider can help you overlap methods to maintain protection. For example, you can have an IUD inserted before your next shot is due. Switching guide.