For information on combination birth control pills, see
Birth control pills, patch, or ring.
How It Works
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
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:
- Take it as soon as you remember even if that means you will take 2 pills in one day. Use another method
of birth control for the next 48 hours to prevent pregnancy.1
- Consider using
emergency contraception if you have had sex in the past 3 to 5 days.
The progestin-only implant 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 implant is a highly effective method of birth
- The implant must be inserted and removed by a trained health
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:
- Are breast-feeding. The mini-pill is a good choice for
breast-feeding mothers. It is very low-dose and does not affect the milk
supply. Breast-feeding further reduces the chance of pregnancy.
- Need short- or long-term birth control that can be stopped at any
time. (But it may take from 12 weeks to 18 months to become pregnant after stopping the birth control shot.)
- Prefer a form of birth control that does not interfere with
- Cannot take estrogen, including those who smoke and are older
than 35; have long-standing, poorly controlled
heart disease; have problems with
blood clots; or have
high blood pressure.
migraine headaches with
auras, or women whose migraines get worse when taking
the estrogen in combination birth control pills.
- Have heavy, painful menstrual periods. Progestin reduces heavy
bleeding and cramping.
anemia from heavy menstrual bleeding.
sickle cell disease. Women with sickle cell disease
may have fewer problems from their disease when using the birth control
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
This method is highly effective,
unless you fail to get a shot after 3 months.2
- Typical use: Among all Depo-Provera users, 3 women out of 100
become pregnant each year.
- Perfect use: Of women who get their shots on schedule, only 3
out of 1,000 become pregnant each year.
This method is very effective,
but you must take the mini-pill at the same time every day.2
- Typical use: Among all mini-pill users, 8 women out of 100
become pregnant each year.
- Perfect use: Of women who take every mini-pill on schedule,
only 3 out of 1,000 become pregnant each year.
This method is extremely effective and
lasts for 3 years.2
- Typical use and perfect use are the same for this method, with
no reported pregnancies from studies.
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
- Irregular menstrual cycles.
- Spotting or bleeding between menstrual periods.
- Sore breasts.
Bloating or weight gain, especially with the birth control shot.
- No menstrual periods. Although mini-pill use can stop periods,
the shot is most likely to do so.
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
Bone thinning. Use of the shot for 2 or more years can cause bone loss,
which may not be fully reversible after stopping the medicine.3
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.4 Talk to your doctor about your risk if you have been using
the shot for longer than 2 years.
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
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.
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Raymond EG (2007). Progestin-only pills. In RA Hatcher et al., eds., Contraceptive Technology, 19th ed., pp. 181–191. New York: Ardent Media.
Trussell J (2007). Choosing a contraceptive:
Efficacy, safety, and personal considerations. In RA Hatcher et al., eds.,
Contraceptive Technology, 19th ed., pp. 19–47. New
York: Ardent Media.
U.S. Food and Drug Administration (2004). Depo-Provera contraceptive injection (medroxyprogesterone acetate injectable suspension). Safety Alerts for Human Medical Products. Available online: http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm154784.htm.
Scholes D, et al. (2005). Change in bone mineral
density among adolescent women using and discontinuing depot
medroxyprogesterone acetate contraception. Archives of Pediatrics and Adolescent Medicine, 159(2): 139–144.
Primary Medical Reviewer
||Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer
||Femi Olatunbosun, MB, FRCSC - Obstetrics and Gynecology
||May 3, 2012