What Is It?
The birth control shot is a long-acting form of progesterone, a
hormone that is naturally manufactured in a girl's ovaries. The
shot is given as an injection in the upper arm or in the buttocks
once every 3 months to protect a girl from becoming pregnant.
How Does It Work?
The hormone progesterone in the birth control shot primarily
works by preventing ovulation (the release of an egg during the
monthly cycle). If a girl doesn't ovulate, she cannot get
pregnant because there is no egg to be fertilized.
How Well Does It Work?
The birth control shot is a very effective method of birth
control. Over the course of 1 year, fewer than 3 out of 100 typical
couples who use the birth control shot every 3 months will have an
accidental pregnancy. The chance of getting pregnant increases if
you wait longer than 3 months to receive your next shot.
In general, how well each type of birth control method works
depends on a lot of things. These include whether a person has any
health conditions or is taking any medications that might interfere
with its use. It also depends on whether the method chosen is
convenient - and whether the person remembers to use it correctly
all of the time
.
Protection Against STDs
The birth control shot
does not
protect against
sexually transmitted diseases (STDs)
. In fact there are studies that show that the birth control shot
may possibly increase the risk of getting certain STDs. Scientists
do not understand why, however.
Couples having sex must always use
condoms
along with the birth control shot to protect against STDs.
Abstinence (not having sex) is the only method that always
prevents pregnancy and STDs.
Possible Side Effects
Many young women who receive the birth control shot will notice
a change in their periods. Other possible side effects include:
- irregular or no menstrual periods
- weight gain, headaches, and breast tenderness
- depression
The U.S. Food and Drug Administration (FDA) has issued a safety
warning with regard to the use of the long-acting progesterone
shot. Studies link this shot to a loss of bone density in women,
although bone density may recover when a woman is no longer getting
the shot.
Doctors are not sure how this type of shot may affect the bone
density of adolescent girls in the future, though. So girls who are
considering the shot as a method of birth control should talk to
their doctors about it. Girls who are receiving the shot should
make sure that they are getting enough calcium each day,
either through their diet or by taking calcium
supplements.
Girls who smoke should be sure to let their doctors know because
smoking may be connected to this bone density loss. Smoking also
increases a girl's chances of the other side effects of the
shot.
Women may notice a decrease in fertility for up to a year
after they stop getting the birth control shot. However, the shot
does not cause permanent loss of fertility and most women can get
pregnant once they stop getting the shot.
Who Uses It?
Every method of birth control should be considered in light of
what works for the individual. Young women who have a hard time
remembering to take birth control pills and who want extremely good
protection against pregnancy use the birth control shot. Also,
nursing mothers can use the birth control shot.
Not all women can - or should - use the birth control shot. In
some cases, medical or other conditions make the use of the shot
less effective or more risky. For example, it is not recommended
for women who have had blood clots, certain types of cancers, or
certain types of migraine headaches. Girls who have had unexplained
vaginal bleeding (bleeding that is not during their periods) or who
suspect they may be pregnant should talk to their doctors.
A girl who is interested in learning more about different types
of birth control, including the shot, should talk to her doctor or
other health professional.
How Do You Get It?
The shot must be prescribed and is given every 3 months in a
doctor's office.
How Much Does It Cost?
Each injection (3 months' worth of birth control) costs
about $60. Many health insurance plans cover the cost of birth
control shots, as well as the cost of the doctor's visit.
Family planning clinics (such as Planned Parenthood) may charge
less.
Reviewed by:
Larissa Hirsch, MD
Date reviewed: March 2009
Originally reviewed by:
Neil Izenberg, MD,
and George A. Macones, MD
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
© 1995-2009 The Nemours Foundation/KidsHealth. All rights reserved.