Progestin-Only Hormonal Birth Control: Pill and Injection

Progestin is a form of progesterone, the hormone that plays a role in the menstrual cycle and pregnancy. Progestin is used in several birth control methods. This page discusses progestin-only pills and the birth control injection. Other progestin-only birth control methods are discussed in Long-Acting Reversible Contraception (LARC): Intrauterine Device (IUD) and Implant.

When it comes to birth control, doctors talk about “typical use” and “perfect use.” Perfect use is when the method is used correctly all the time. For example, if you take birth control pills, perfect use means never forgetting to take a pill. Typical use reflects what happens in real life. Sometimes people forget to take pills.

Progestin-Only Pills: With typical use, 9 in 100 women get pregnant during the first year of using progestin-only pills. With perfect use—meaning people never forget to take a pill and always take them at the same time every day—fewer than 1 in 100 women get pregnant during the first year of using progestin-only pills. Taking a pill at the same time each day is important for this method to be effective.

Birth Control Injection: The injection is slightly more effective than progestin-only pills. With typical use, 6 in 100 women get pregnant during the first year of using the injection. With perfect use—meaning people get repeat shots on time every 13 weeks—fewer than 1 in 100 women get pregnant during the first year of using the injection.

These methods help prevent pregnancy, but they do not protect against sexually transmitted infections (STIs). If you are at risk of getting an STI, you should also use a condom or dental dam for STI protection. Read How to Prevent Sexually Transmitted Infections (STIs) to learn more.

Progestin-only pills are sometimes called “mini-pills.” The pills come in packs of 28 and should be taken one a day at the same time each day. One type of progestin-only pill comes with 24 active pills (with progestin) and four inactive pills (with no progestin) in each pack.

If you have trouble remembering pills, use an alarm or a smartphone app to remind you. Do not skip pills for any reason. Missing pills or taking pills at different times each day makes the birth control less effective.

The progestin in the pills has several effects in the body that help prevent pregnancy:

• The mucus in the cervix thickens, making it difficult for sperm to enter the uterus and fertilize an egg.

• Progestin stops ovulation, but it does not do so consistently. About 4 in 10 women who use progestin-only pills will continue to ovulate.

• Progestin thins the lining of the uterus.

You can start using this method for the first time at any point during your menstrual cycle. You do not need a physical exam, such as a pelvic exam or cervical cancer screening, to get a prescription. But you and your obstetrician–gynecologist (ob-gyn) or other health care professional should be reasonably sure you are not pregnant. Follow these directions:

• If you start taking the pills within the first 5 days after the start of your menstrual period, no additional birth control method is needed.

• If you start taking the pills more than 5 days after the start of your period, use an additional birth control method or avoid sexual intercourse (vaginal sex) for the next 2 days.

• If you are switching from another form of birth control, simply stop using the other method at the same time you start the progestin-only pills. If it has been more than 5 days since your period started, use an additional birth control method or avoid sex for the next 2 days.

• If you are switching from an intrauterine device (IUD), you have a few options. You can wait until you have been taking the pills for at least 2 days to have the IUD removed. Or you can use another form of birth control or avoid sex for the 2 days before removing the IUD and starting the pills.

With most progestin-only pills, if you miss a pill by more than 3 hours, you should take it as soon as possible and use a backup method of birth control (such as condoms) or avoid having vaginal sex for the next 2 days.

Also, if you have vomiting or severe diarrhea within 3 hours after taking a pill, the progestin may not be absorbed completely by your body. Keep taking your pills but use a backup method until 2 days after your vomiting or diarrhea stops.

With the progestin-only pill pack that has 24 active pills and 4 inactive pills, there is a little more flexibility. If you occasionally miss a pill, you can take the next one within 24 hours. But the goal should still be to take the pills at the same time each day. Missing pills makes the birth control less effective.

Certain medications may interfere with the effectiveness of the progestin-only pill. These medications include

• rifampin, a drug used to treat certain infections

• some drugs used to prevent seizures

• some drugs used to treat human immunodeficiency virus (HIV)

Your ob-gyn or other health care professional should ask about any medications you are taking before prescribing progestin-only pills.

Progestin-only pills offer benefits beyond birth control. For example, you may have less bleeding or stop having periods altogether while taking these pills. This can be helpful if you have heavy or painful periods, or if you prefer to have less or no bleeding.

Unlike birth control pills that contain estrogen and progestin, progestin-only pills do not increase the risk of high blood pressure or cardiovascular disease. Also, you can take progestin-only pills even if you have certain health conditions, such as a history of deep vein thrombosis (DVT) or uncontrolled high blood pressure.

Yes, progestin-only pills can be used immediately after childbirth, even if you are breastfeeding. The pills can also be used immediately after a miscarriage or abortion.

If you want to get pregnant, simply stop taking the pills. You can start trying to get pregnant right away. Your chances of getting pregnant are the same as for other women your age who have not used progestin-only pills.

Progestin-only pills may not be a good choice if you have certain medical conditions, such as some forms of lupus. Do not take progestin-only pills if you have breast cancer or a history of breast cancer.

Bleeding changes are the most common side effect. Bleeding may be unpredictable. You may have short cycles of bleeding or spotting. Less commonly, you may have heavy bleeding or no bleeding at all. It is not clear whether these changes get better with time. Other side effects may include headaches, nausea, and breast tenderness.

Bleeding may be more predictable with the progestin-only pill packs that include 4 days of inactive pills. You may have your period during these days.

The birth control injection contains the hormone depot medroxyprogesterone acetate (DMPA). This hormone protects against pregnancy for 13 weeks. You need four injections a year while you are using this form of birth control.

The DMPA in the injection has several effects that work together to prevent pregnancy:

• It stops ovulation.

• It thickens and decreases the amount of cervical mucus. This makes it difficult for sperm to enter the uterus and fertilize an egg.

• It thins the lining of the uterus.

Injections are given by an ob-gyn or other health care professional. The first shot can be given at any time during your menstrual cycle as long as you and your health care professional are reasonably sure you are not pregnant. Follow these directions:

• If you get your first shot within the first 7 days after the start of your period, no additional birth control method is needed.

• If you get your first shot more than 7 days after the start of your period, you need to use an additional birth control method or avoid sex for the next 7 days.

• If you are switching from another form of birth control, simply stop using the other method at the same time you get your first shot. If it has been more than 7 days since your period started, use an additional birth control method or avoid sex for the next 7 days.

• If you are switching from an IUD, you have a few options. You can keep your IUD until at least 7 days after your first injection and then have the IUD removed. Or you can use a barrier method (such as condoms) or avoid sex for 7 days before removing the IUD and getting the first shot.

The injection is most effective when you get it every 13 weeks. Injections can be given up to 2 weeks late (15 weeks from the last injection).

If you are more than 2 weeks late for a repeat injection, you can have it as long as you and your health care professional are reasonably sure that you are not pregnant. You should use an additional birth control method or avoid sex for the next 7 days.

DMPA has benefits that are not related to birth control, including

• reducing the risk of cancer of the uterus if used long term

• reducing pelvic pain caused by endometriosis

DMPA may relieve certain symptoms of sickle cell disease and seizure disorders. It may reduce the bleeding associated with uterine fibroids. And it may protect against pelvic inflammatory disease (PID).

Some women report weight gain while using the DMPA injection. Among women who gained weight, the average amount of weight gained was less than 5 pounds.

Yes, the injection can be used immediately after childbirth, even if you are breastfeeding. It can also be used immediately after a miscarriage or abortion.

It takes an average of 10 months to get pregnant after stopping the injection. For some women, it can take longer. If you are planning a pregnancy, talk with your ob-gyn about when to stop using the birth control injection.

DMPA may cause irregular bleeding. During the first year of use, it’s common to have longer periods of bleeding or spotting. Irregular bleeding usually decreases with each injection.

After the first year, about 1 in 10 women continue to have irregular bleeding. Many women have only light bleeding or even stop all bleeding after 1 year of use.

• Bone loss may occur while using the birth control injection. When the injections are stopped, at least some and sometimes all of the bone that is lost is gained back. Any bone loss that occurs is not likely to increase the risk of bone fracture now or later in life. The injection can still be safely used as a long-term birth control method.

• If you have multiple risk factors for cardiovascular disease, like smoking, older age, or diabetes mellitus, you may be at increased risk of cardiovascular disease while using DMPA. This increased risk may last for some time after the method is stopped.

• If you have a history of stroke, vascular disease, or poorly controlled high blood pressure, you may also be at increased risk of cardiovascular disease while using this method.

Bone Loss: The gradual loss of calcium and protein from bone, making it brittle and more likely to break.

Cardiovascular Disease: Disease of the heart and blood vessels.

Cervix: The lower, narrow end of the uterus at the top of the vagina.

Deep Vein Thrombosis (DVT): A condition in which a blood clot forms in veins in the leg or other areas of the body.

Dental Dam: A thin piece of latex or polyurethane used between the mouth and the vagina or anus during oral sex. Using a dental dam can help protect against sexually transmitted infections (STIs).

Diabetes Mellitus: A condition in which the levels of sugar in the blood are too high.

Egg: The female reproductive cell made in and released from the ovaries. Also called the ovum.

Endometriosis: A condition in which tissue that lines the uterus is found outside of the uterus, usually on the ovaries, fallopian tubes, and other pelvic structures.

Estrogen: A female hormone produced in the ovaries.

Fibroids: Growths that form in the muscle of the uterus. Fibroids usually are noncancerous.

High Blood Pressure: Blood pressure above the normal level. Also called hypertension.

Hormone: A substance made in the body that controls the function of cells or organs.

Human Immunodeficiency Virus (HIV): A virus that attacks certain cells of the body’s immune system. If left untreated, HIV can cause acquired immunodeficiency syndrome (AIDS).

Intrauterine Device (IUD): A small device that is inserted and left inside the uterus to prevent pregnancy.

Lupus: An autoimmune disorder that affects the connective tissues in the body. The disorder can cause arthritis, kidney disease, heart disease, blood disorders, and complications during pregnancy. Also called systemic lupus erythematosus or SLE.

Menstrual Cycle: The monthly process of changes that occur to prepare a woman’s body for possible pregnancy. A menstrual cycle is defined as the first day of menstrual bleeding of one cycle to the first day of menstrual bleeding of the next cycle.

Menstrual Period: The monthly shedding of blood and tissue from the uterus.

Miscarriage: Loss of a pregnancy that is in the uterus.

Obstetrician–Gynecologist (Ob-Gyn): A doctor with special training and education in women’s health.

Ovulation: The time when an ovary releases an egg.

Pelvic Inflammatory Disease (PID): An infection of the upper female genital tract.

Progesterone: A female hormone that is made in the ovaries and prepares the lining of the uterus for pregnancy.

Progestin: A synthetic form of progesterone that is similar to the hormone made naturally by the body.

Sexual Intercourse: The act of the penis of the male entering the vagina of the female. Also called “having sex” or “making love.”

Sexually Transmitted Infections (STIs): Infections that are spread by sexual contact. Infections include chlamydia, gonorrhea, human papillomavirus (HPV), herpes, syphilis, and human immunodeficiency virus (HIV, the cause of acquired immunodeficiency syndrome [AIDS]).

Sickle Cell Disease: An inherited disorder in which red blood cells have a crescent shape. The disorder causes chronic anemia and episodes of pain.

Sperm: A cell made in the male testicles that can fertilize a female egg.

Stroke: A sudden interruption of blood flow to all or part of the brain, caused by blockage or bursting of a blood vessel in the brain. A stroke often results in loss of consciousness and temporary or permanent paralysis.

Uterus: A muscular organ in the female pelvis. During pregnancy, this organ holds and nourishes the fetus. Also called the womb.