Birth control pill — Mayo Clinic experts answer frequently asked questions about taking the pill.
If you use the birth control pill — that is, an oral contraceptive — you're probably happy with its convenience and reliability. Still, you may have many questions about the potential effects of birth control pills on your overall health. Here's what Mayo Clinic specialists have to say about women's health and oral contraceptive use.
Can you use ordinary birth control pills continuously to prevent having a period?
It's possible to prevent your period with continuous use of any birth control pill. This means skipping the placebo pills and starting right away on a new pack. Some evidence suggests an advantage to this type of pill regimen. By continuously taking the pill, you prevent hormonal fluctuations that are responsible for bleeding, cramping, headaches and other discomforts associated with getting your period. However, you're at greater risk of breakthrough bleeding — bleeding between periods. Continuous use of your birth control pills works best if you're taking a monophasic pill — with the same hormone dose in the three weeks of active pills. If you're taking a triphasic pill — with a different hormone dose each week of the active pill phase — using them continuously carries a much higher rate of breakthrough bleeding.
You may find continuous use of birth control pills a convenient way to avoid having your period during an important occasion or trip. Taking a monthly regimen birth control pill continuously is fine for about three months, but then you should plan on taking the placebo pills so that you'll have a menstrual cycle.
Is there an advantage to waiting a few months after stopping the pill before trying to conceive?
For the purpose of dating the pregnancy — estimating when you ovulated and when your baby is due — it's somewhat advantageous to have at least one normal period before conceiving.
In the past, doctors had concerns that if you conceived immediately after stopping the pill, you had a higher risk of miscarriage. However, these concerns have proved to be largely unfounded.
If you plan to wait a few months, use a backup form of birth control while your menstrual cycles get back to normal.
Will a pregnancy test be accurate if you're taking the birth control pill?
You can get accurate results from a pregnancy test while you're on the pill. Pregnancy tests work by measuring a specific pregnancy-related hormone — human chorionic gonadotropin (HCG) — in your blood or urine. The active ingredients in birth control pills don't affect how a pregnancy test measures the level of HCG in your system.
Can you use several birth control pills at once for emergency contraception?
It's possible to use standard estrogen-progestin birth control pills for emergency contraception, but check with your doctor for the proper dose and timing of the pills.
There is a special type of contraceptive pill that's specifically designed to keep you from becoming pregnant if you've had unprotected vaginal intercourse. An emergency contraception pill (Plan B) — also called the "morning-after pill" — contains a higher dose of progestin than is found in other birth control pills and is available over-the-counter for women age 18 and older. Otherwise, check with your doctor, local emergency room or Planned Parenthood clinic if you're in need of emergency contraception.
Can you get pregnant during the week that you take the nonactive (placebo) pills?
Taking the nonactive pills doesn't put you at higher risk of unintended pregnancy. If you're taking your birth control pills exactly as directed, they're 98 percent to 99 percent effective at preventing pregnancy.
If, however, you've missed a dose — or several doses — of your birth control pills during a cycle, you might be at higher risk of unintended pregnancy during that cycle. To be safe, use a backup form of contraception, such as a condom.
How do birth control pills affect your risk of cancer?
Scientific evidence suggests using birth control pills for longer periods of time increases your risk of some cancers, such as cervical cancer and liver cancer, but it also decreases your risk of other types of cancer, including ovarian cancer and endometrial cancer.
The effect of birth control pills on breast cancer risk isn't quite clear. However, some studies do show a link between pill use and breast cancer. Key factors seem to be how many years you take the pill and how recently you last used the pill. In one study, use of birth control pills led to a higher risk of premenopausal breast cancer in women who took the pill for four or more years before having a baby. Other evidence suggests that 10 or more years after you stop taking the pill, your breast cancer risk returns to the same level as if you had never taken birth control pills.
Do birth control pills affect blood pressure?
Birth control pills may increase blood pressure. The risk of high blood pressure in women who take birth control pills also increases with age and the duration of use.
If you take birth control pills, have your blood pressure checked regularly. If you already have high blood pressure, consider an alternative form of birth control. If you do choose to take the pill, have your blood pressure closely monitored by your doctor.
If you develop high blood pressure while taking the pill, give serious thought to switching to another form of contraception.
Can antibiotics decrease the effectiveness of birth control pills?
The effects of antibiotics on birth control pills may be overstated — except in the case of one antibiotic, rifampin. Studies clearly show that rifampin decreases the effectiveness of birth control pills in preventing ovulation. However, rifampin isn't a widely used antibiotic. Chances are you wouldn't be taking it unless you had tuberculosis or had tested positive for the disease.
Hypothetically speaking, other antibiotics, particularly penicillin and tetracycline derivatives, could impair the effectiveness of birth control pills. However, no large studies have proved such an effect.
Researchers can't rule out the possibility that a small percentage of women may experience decreased effectiveness of birth control pills while taking an antibiotic. And if you're taking a newer, extremely low-dose oral contraceptive, you could be more susceptible to these potential effects from antibiotics. If you're concerned, consider using a barrier method of contraception for the duration of your antibiotic prescription.
Last Updated: 05/22/2007
