Dear sandrailmo,

The shot is a reversible prescription method of birth control. It is injected every 12 weeks. The injection contains the hormone progestin, which is similar to the progesterone made by a woman's ovaries.

The shot provides protection from pregnancy immediately if a woman gets the injection during the first five days of her period. Otherwise, a woman needs to use an additional method of contraception for the first week. Remember, the shot provides no protection against sexually transmitted infections. Latex and female condoms can reduce the risk of infection.

Some women experience side effects from using the shot. The most common side effect is irregular bleeding. Some women stop menstruating completely after prolonged use. Click here for an important update about the shot.

The surest way for a woman to find out if she's pregnant is to take a pregnancy test. Call 1-800-230-PLAN to schedule a confidential pregnancy test at a Planned Parenthood health center in your area.

Hope this information helps!

Take care,

teenwire.com^® Editors

This column is for informational purposes only and is not intended to constitute medical advice, diagnosis, or treatment. If you have a medical problem, please call toll-free 1-800-230-PLAN for an appointment with the Planned Parenthood health center nearest you.