Progestin-Only Hormonal Methods (Mini-Pills, Implants, and Shots)
For information on combination birth control pills, see Birth control pills, patch, or ring.
How It Works
Progestin-only birth control methods, including pills (called "mini-pills"), implants, and shots, prevent the ovaries from releasing an egg (ovulation), thicken mucus at the cervix so sperm cannot enter the uterus, and in rare cases, prevent a fertilized egg from implanting in the uterus.
Birth control mini-pills
Progestin-only mini-pills come in a monthly pack. To be effective, the pills must be taken at the same time each day. If you take a pill more than 3 hours late:
The progestin-only implant (such as Implanon) releases hormones that prevent pregnancy for 3 years. The actual implant is a thin rod about the size of a matchstick. This is inserted under the skin on the inside of the upper arm.
The birth control shot, such as Depo-Provera, is effective for 12 to 13 weeks.
Why It Is Used
Progestin-only mini-pills, implants, and shots are good choices for women who:
How Well It Works
Shots and implants are highly effective methods of birth control.
Progestin-only mini-pills are very effective, but combination hormone pills are even more effective. Also, the mini-pill has to be taken at the same time every day to work correctly.
This method is highly effective, unless you fail to get a shot after 3 months.4
This method is very effective, but you must take the mini-pill at the same time every day.4
This method is extremely effective and lasts for 3 years.4
Medicines that can interfere with hormonal birth control
Some combinations of medicine may affect the birth control hormones in your body, making them too strong or too weak. This may increase your chance of becoming pregnant. Or a new medicine may be less likely to work because you have birth control hormones in your body. Talk with your doctor or pharmacist to make sure that the medicines you take are not causing problems when you are using hormonal birth control.
Most side effects of the progestin-only birth control methods go away after the first few months of use. Side effects include:
Less common progestin side effects include depression and darkening of the skin on the upper lip, under the eyes, or on the forehead (chloasma).
Risks of the shot
For teens, bone loss from the shot is a concern. Teens are normally building bone mass as they grow. This is why it is very important for teens to get enough calcium and vitamin D when using the shot. A small study among teens showed that bone loss from the shot was reversed after the teens stopped getting the shots.5 Talk to your doctor about your risk if you have been using the shot for longer than 2 years.
Infection risk. One recent study has shown that using the shot may make chlamydia or gonorrhea infection more likely if you are exposed to these bacteria.2 If you have any risk of being exposed to sexually transmitted diseases, use condoms.
Progestin risk after having gestational diabetes
Breast-feeding women can use the mini-pill or shot without worrying about effects on their milk supply or the baby. But using progestin-only birth control after having gestational diabetes appears to make it more likely that you will develop diabetes.1
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
Progestin-only mini-pills may not be as effective if you are vomiting or have diarrhea. Use another method of birth control for 7 days after vomiting or diarrhea, even if you have not missed any pills.
eMedicineHealth Medical Reference from Healthwise
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