How Does Hormonal Birth Control Work?
Unlike most non-hormonal birth control options that don’t affect your hormones, hormonal birth control works by mimicking the body’s natural hormones to stop ovulation.
“Hormonal birth control pills stabilize the lining of the uterus, prevent ovulation and can thicken your cervical mucus — which prevents sperm from entering and causing pregnancy,” Dr. Dickinson says.
“This process happens when taking your active birth control pills, which is for about three weeks every month. During the final week, you take placebo pills that lead to your menstrual cycle because of the decline in hormones.”
Using Birth Control to Stop Your Period
If one of your goals for taking hormonal birth control is to skip your monthly menstrual cycle altogether, Dr. Dickinson says there’s a method for that.
“Combination hormonal birth control can eliminate your cycle if taken continuously. It involves only taking the active pills and skipping the placebo pills each month. This stabilizes the lining of your uterus, so it doesn’t shed."
She adds, "At a higher dose, progesterone-only pills like Aygestin and Provera, can also be used for eliminating cycles when skipping the placebos. However, at a higher dose, progesterone-only pills aren’t used as birth control, because they haven’t undergone clinical studies on preventing pregnancy. The opposite is true for low-dose progesterone-only pills, such as Micronor or Slynd. They aren’t guaranteed to eliminate menstrual cycles when taken continuously, but they're used as birth control.”
Dr. Dickinson says it's OK to stop your menstrual cycle while on hormonal birth control, if that's your preference. There aren't any health benefits associated with keeping your cycle while on hormonal birth control – some women simply choose not to because of the added convenience.
Types of Hormonal Birth Control
Pill, Patch and Ring
How it Works: A combination of estrogen and progesterone is used to prevent ovulation and thicken cervical mucus. The pill is taken by mouth every 24 hours, while the patch is applied to your body on the same day every week. The ring is self-inserted into the vagina every three weeks.
Effectiveness: With perfect use, they’re 99% effective at preventing pregnancy. With typical use, such as forgetting to take the pill around the same time every day, they’re about 93% effective.
How it Works: It’s inserted into the upper arm where it can't be seen, but felt, with your fingers. It suppresses ovulation, thickens cervical mucus and alters the endometrial lining.
Effectiveness: It’s the most effective of all forms of birth control at preventing pregnancy with more than 99% effectiveness.
Intrauterine Device (IUD)
How it Works: A t-shaped plastic device is placed inside the uterus during a procedure with your doctor. Once inserted, the IUD creates an environment unfavorable for sperm. Progestin-containing IUDs include the Mirena and Liletta (both can be used up to 8 years individually), Kyleena (up to 5 years) or Skyla (up to 3 years).
Effectiveness: It’s more than 99% effective at preventing pregnancy.
How it Works: A doctor puts this progesterone-only injectable in the muscle of the upper arm once every three months. It stops ovulation and thickens cervical mucus.
Effectiveness: It’s about 99% effective at preventing pregnancy with perfect use and 96% effective with typical use.
Hormonal Birth Control Side Effects
All medications have side effects, but here's what to potentially expect when taking hormonal contraception:
- Increased blood pressure
- Mood changes
- Weight gain
- Irregular bleeding
- Breast tenderness
- NauseaPain/cramping at the insertion or injection site
If you experience any of these symptoms while taking hormonal birth control, Dr. Dickinson suggests giving it some time, if you can, before calling it quits and trying something else.
“Typically, we recommend using the same birth control for three months, or at least three cycles, before switching. This allows your body enough time to adjust to the medication and, hopefully, for the symptoms to subside.”
In some cases, medical conditions can get worse when taking hormonal birth control containing estrogen. You should talk to your doctor about what type of contraceptive is best for you if you currently experience, or have in the past, the following:
“Progesterone-only birth control may be better tolerated but shouldn’t be used if you have lupus or a history of breast cancer,” Dr. Dickinson says.
While combination birth control methods are safe for most women, Dr. Dickinson says they’re associated with a small, elevated risk of stroke, heart attack and blood clots with both deep vein thrombosis and pulmonary embolisms.
According to the American College of Obstetricians and Gynecologists, these risks primarily pertain to women older than 35 years of age, are avid smokers or who have several risks for cardiovascular disease, including many of those listed above.
In addition to talking with your doctor, Dr. Dickinson recommends patients use a free app developed by the U.S. Medical Eligibility Criteria (USMEC) to determine what hormonal birth control is safe for certain medical conditions.
What are the Benefits of Hormonal Birth Control?
From serious to purely bothersome medical conditions, hormonal contraception can be beneficial for more than preventing pregnancy. Dr. Dickinson says it’s commonly prescribed to help with a number of health concerns women experience, including:
- Regulating irregular menstrual cycles
- Lightening otherwise heavy menstrual cycles
- Decreasing pain and cramping during periods
- Stopping the menstrual cycle altogether, if taken continuously
- Improving acne
- Preventing menstrual migraines from fluctuating hormones
- Alleviating excessive sweating
- Improving anemia
- Helping with mood changes during periods
How Long Does it Take Hormonal Birth Control to Leave Your Body?
If you’re trying to get pregnant, or simply want to stop taking hormonal birth control, it doesn’t stay in your system for very long once you discontinue use.
“Most hormonal birth control is out of your system within 24 hours, but it may take a few months for the uterine lining to thicken enough to support a pregnancy. The Depo-Provera shot can stay in your system for up to six months.”
How Long Can You Take Hormonal Birth Control?
Dr. Dickinson says you can take hormonal birth control until menopause, most often occurring in women between ages 45 and 55, as long as there are no other health conditions that could be complicated by taking estrogen.
Additionally, some birth control methods are designed to stay in your body longer based on the brand’s guidance. For example, the Mirena intrauterine device (IUD) works to prevent pregnancy for up to eight years, while the Kyleena IUD works for five years and the Nexplanon implant works for three.
What To Do If You Forget to Take Your Birth Control Pill
If you’re taking a birth control pill, timing is key for it to be effective at preventing pregnancy.
Remembering to take the pill within the same two-hour time frame everyday can be difficult. To prevent yourself from forgetting, you can try working it into a routine that’s already familiar to you — such as taking it right when you wake up or before bed.
If you miss a day, or take the pill outside of the two-hour window, Dr. Dickinson advises taking the late or missed pill as soon as possible. If you miss two or more pills, or it’s been 48 hours since your last dose, do a combination of these three things:
Take the most recent pill as soon as you can AND
Avoid having sex until you’ve taken the pills for seven days in a row OR
Use backup contraception, such as a condom