How Does It Work?

Depo-Provera prevents pregnancy in three ways:

1. It inhibits ovulation.
2. It changes the cervical mucus to help prevent sperm from reaching the egg.
3. It changes the uterine lining to prevent a fertilized egg from implanting in the uterus.

Does It Protect Against STIs?

STI stands for sexually transmitted infection. STI risk varies depending on how you choose to protect yourself and your partner during sexual or intimate activities.

Depo-Provera does not protect against STIs.

Does It Protect Against Pregnancy?

Yes. The chances of getting pregnant while using Depo-Provera are:

• Typical use: 0.3 percent
• Perfect use: 0.3 percent

Advantages and Disadvantages

Advantages:

• It has a similar effect to the pill and mini pill, but requires less effort. 
• The female doesn't have to remember to take daily pills; the only task is to visit a healthcare provider every three months to receive the injection.
• It can be used by women who cannot take estrogen or who require medication for seizures.
• It reduces menstrual cramps and anemia.
• It helps prevent serious health risks such as endometrial cancer and ovarian cysts.

Disadvantages:

After a certain time period, you have to repeat the injection. If this time period lapses, you can get pregnant and you must take a pregnancy test before getting a repeat injection.

Side Effects

The most common side effect is irregular bleeding in 70 percent of women in the first year and in 10 percent of women thereafter. Absence of bleeding is common in 80 percent of women after two years.

The less common side effects include:

• Increased appetite and weight gain.
• Headaches.
• Sore breasts.
• Nausea.
• Depression.
• Nervousness.
• Dizziness.
• Skin rashes or spotty darkening of the skin.
• Hair loss or increased hair on face or body.
• Increased or decreased sexual desire.
• Vaginal dryness.
• Bone loss if Depo-Provera is started at a young age and is used more than two to five years. This bone loss is reversible if Depo-Provera is stopped.
• Side effects don't stop until the shot wears off, which may take 12 to 14 weeks. 
• If pregnancy is desired, it takes 12 to 18 weeks to get pregnant after the last shot is taken (sometimes longer).
• In the rare case that pregnancy occurs during the use of Depo-Provera, there is an increased chance of ectopic (tubal) pregnancy, a dangerous condition.

Last Reviewed: January 2019