Birth Control Pill vs. Shot: Effectiveness and Differences in Side Effects and Risks

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

  • Medical Editor: Charles Patrick Davis, MD, PhD
    Charles Patrick Davis, MD, PhD

    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

Side Effects of Birth Control Pills

Combination birth control pills contain estrogen and progestin, and are about 99% effective in preventing pregnancy if you take them as directed. The mini-pill only contains estrogen, and is up to 95% effective.

Examples of side effects of birth control pills include weight gain, irregular bleeding, mood changes, nausea, and breast tenderness.

Birth control pill vs. the Depo-Provera shot, which method is right for you?

The choice of what birth control method is highly personal and depends upon many factors. It is important to consider your age, overall health status, and how long you would like the birth control method to last. It also is important to look at how well each method works (its effectiveness) in preventing pregnancy, how easy each method is for you to use, and any side effects or drug interactions it may cause. The birth control pill ("the pill", oral contraceptives) and the Depo-Provera hormone injection ("shot") are just two of the many choices a woman has to prevent pregnancy. This article compares birth control pills (known as oral contraceptives) with the birth control shot (Depo-Provera injection).

Similarities and differences between how birth control pills vs. the shot work, and frequency of administration

Birth control pills and the birth control Deop-Provera shot are both hormonal methods of birth control. This means that they work by changing hormone levels in your body, preventing pregnancy from occurring. The hormones in birth control pills prevent release of an egg, or ovulation.

Birth control pills are available as combination pills, containing the hormones estrogen and progestin, or as mini-pills containing progestin only. Both typically come in packs of 28 pills, and you take one pill daily. With combination pills, the last 7 pills in the pack do not contain hormones, and while you are taking these non-hormone pills, your menstrual period occurs. The menstrual period also occurs during the last 7 days of the progestin-only pill packs. Some newer types of birth control pills are taken continuously for a few months without the inactive pills, before a menstrual period occurs. The pill also work to make the cervix (opening to the womb or uterus) and the uterus itself unfavorable for a pregnancy to begin.

The birth control shot is known as Depo-Provera (and the newer low-dose Depo-SubQ Provera 104). It contains the hormone progestin and prevents pregnancy for three months in a row. Like the hormones in birth control pills, the progestin in the shot make the environment in the uterus unfavorable to begin a pregnancy and may stop ovulation.

Birth control pill vs. shot effectiveness in preventing pregnancy

Both the pill and the shot are very effective methods of birth control. When combination birth control pills are taken correctly, they are up to 99% effective in preventing pregnancy. Progestin-only pills are about 95% effective. The birth control shot (Depo-Provera) also is about 99% effective in preventing pregnancy (average annual failure rate is about 3%).

Do birth control pills or shot cause weight gain?

Yes, women have reported weight gain while taking oral contraceptives and using the Depo-Provera shot.

Similar side effects of the pill vs. shot

Both methods can cause tenderness or soreness of the breasts. Other side effects of oral contraceptives and the Depo-Provera shot include headaches and mood changes. Both methods can lead to a decreased interest in sex (decreased libido) in some women.

Medically Reviewed by a Doctor on 6/15/2017

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