The Combined Oral Contraceptive Pill (“The Pill”)

iStock 000005654093SmallThe oral contraceptive pill is still the mainstay of reversible contraception.

1.  What are the benefits of the pill?

2.  Is the pill safe? What are the risks?

3.  When should I stop the pill?

4.  Who should not take the pill?

5.  How does the pill work?

6.  Does the pill impact my future chances of pregnancy?

7.  How do I take the pill?

8.  What if I miss a pill or pills?

9.  What if I start bleeding in the middle of my pill pack?

10.  What side effects should I report right away?

11.  Are there medications I shouldn't take when on the pill?

12.  What's in the Pill?

13.  Other Resources

See also ACOG's Patient Brochures: Birth Control Pills, Birth Control, and Birth Control for Teens.

What are the benefits of the pill?

Contraception - The pill is 97% effective with "typical" use, and 99.9% effective with "ideal" use.

Non-contraceptive benefits: Lower risk for endometrial and ovarian cancer, less risk of ectopic pregnancy, more regular menses (shorter, less flow, less cramping and less anemia), less tubal disease, possibly less endometriosis, possibly protection against rheumatoid arthritis, possibly fewer ovarian cysts and fibroids, possibly increased bone density, less acne.

Is the pill safe? What are the risks?

The quick answer is "overall yes, the benefits outweigh the risks for most young healthy women". The pill does slightly increase risks of stroke, heart attack, premenopausal breast cancer (fairly rare to begin with, but does increase by about 20%), rare liver cancers and benign liver tumors, gall bladder disease, clots in your leg that can go to your lungs. Generally, the risks of unwanted pregnancy outweigh most of these risks for young healthy women.

The pill actually PROTECTS against endometrial cancer (it is one of the treatments for PCOS), and against ovarian cancer (decreases it by 40%).

Please note that the pill does NOT protect against sexually transmitted diseases.

When should I stop the pill?

If you are healthy in every way, you can take the pill right up to age 50 to 52.

If you are a smoker, or are obese, or have high blood pressure, or other serious risks for cardiac disease and stroke, you should stop at age 35.

Most studies indicate that the risks of premenopausal breast cancer rise after 10 years of use. Many women prefer to limit their pill use to 10 lifetime years, although this is not absolutely necessary.

Who Should Not Take the Pill?

If there is a personal history of a blood clot, you should NOT take the pill. If a close family relative (parent or sibling) has a history of a blood clot, you should not take the pill.

If you are a smoker, especially over age 35, your risks are higher. Smokers over age 35 should not take the pill.

If you have liver disease, you should not take the pill.

Other contraindications:

  • Known or suspected pregnancy
  • Undiagnosed abnormal vaginal bleeding
  • Known or suspected breast cancer
  • Migraines that are preceded by visual change
  • Over age 35 with high blood pressure

How does the pill work?

The pill stops your body from ovulating (because the brain detects that there is plenty of estrogen around, and does not give the signal to the ovaries to ovulate).

Does the pill impact my future chances of pregnancy?

No. When you stop the pill you return immediately to the hormonal state you would have been in if you had not taken the pill. If you gained weight and became insulin resistant, your body stops ovulating and your periods stop. Sometimes if women experience the weight gain during the time they are on the pill, the pill masks the periods stopping, and they don't notice that they have become insulin resistant and stopped until they discontinue the pill. But the pill did not cause the periods to stop; instead the insulin resistance did. Treating insulin resistance usually causes the periods to restart.

How do I take the pill?

You can start the pill on any day you choose. Just be sure you remember what day of the week is your "start day". Sunday is convenient for people using the pill on a cycle, because typically you don't get your period on the weekend. Once you start, it is important to get into a routine in which you remember to take your pill every day, at the same time every day. Try to time it with something you do every day, like brushing your teeth. You should use a back up method (eg condoms) for the first month of the pill.

You can take the pill on a "cyclic" basis, or a "continuous" basis.

The "cycling" method means that you take the pill for three weeks, then take a sugar pill (or nothing) for a period of 3 to 7 days. During this time you have a monthly bleed.

The "cycles" of the pill pack are entirely artificial. You are not actually having periods on the pill but "withdrawal bleeds" in response to stopping the progestin in the pill. The pill was developed that way to make it more acceptable to society as it was introduced. But there is no good physiologic reason why you need to have a withdrawal bleed each month. You are in a "steady state" on the pill.

That's good news, because it means you can "tinker". If you have a wedding, a vacation, an important event of any kind, and don't want to be bothered with your period, you can extend your cycle by "skipping the placebo" pills.

It also means you can extend the cycle out to 9 to 12 weeks. Not only is this more convenient, but it decreases risks of anemia, it decreases risk of pregnancy, it decreases pain associated with menses, and decreases cyclic PMS symptoms. Breakthrough bleeding is increased a little though.

What if I miss a pill or pills?

You are at increased risk of pregnancy if you miss a pill. If you miss one, take it as soon as possible and resume your cycle. Back-up is not necessary. If you miss two pills, take two daily for two days, and use a back up method (such as condoms, which you should use anyway to prevent STDs) for at least 7 days. If you miss 3 pills, you should definitely use a back up, and simply start a new pack.

What if I start bleeding in the middle of my pill pack?

This is very common. It happens most frequently in the first three months, and gets less and less common over time. The more "low dose" your pill is, the less your serious risks, but the more common break-through bleeding is. Most importantly, be assured that breakthrough bleeding does NOT make the pill less effective. Sometimes it can be effectively treated by adding a little extra estrogen for a few weeks, but usually it just goes away with time.

What side effects should I report right away?

The following are WARNING signs and although rare, should be reported immediately to the clinic:

Abdominal or chest pain, trouble breathing, severe headaches, visual problems, leg pain or swelling.

The following are nuisance side effects that you can expect commonly in the first three months, and do not need to be reported unless they are becoming such a nuisance you are considering stopping the pill:

Breakthrough bleeding, headaches, water retention, breast tenderness, mood changes, headaches, minor weight gain, nausea. They all tend to become less with time.

Are there medications I shouldn't take when on the Pill?

Obviously, other hormones containing estrogen or progesterone should only be used under careful supervision. Chemotherapy may be a contraindication. Antibiotics and anti-seizure medications may or may not make the pill less effective, so these should be discussed with your physician. To be safe, a backup method is advisable.

What's in the Pill?

It is typically consists of combined estrogen and progestin. The estrogen used in the oral contraceptive pill is ethinyl estradiol. Estradiol is the strongest and most powerful of the several estrogens that your body normally produces. The estrogen in the pill is not quite estradiol, but is equally as strong, or stronger. It has been chemically modified as little so that it can be absorbed when taken by mouth. The progestins are are synthetic compounds somewhat similar to real progesterone which fall into four main categories: (1) levonorgestrel; (2) norgestimate; (3) gestodene or (4) desogestrel. They all tend to act like real progesterone at the level of the uterine lining, but can compete with real progesterone elsewhere in your body.  For some people, progestins induce insulin resistance, and can thus contribute to weight gain.

The estrogen is responsible for most of the serious but rare side effects of the pill, such as the slight increase in clots in your legs that can go to your lungs, heart attacks and stroke. It is also typically responsible for the breast tenderness.

The progestins are responsible for most of the nuisance side effects, such as bloating, mood changes, irregular bleeding ("breakthrough bleeding"), headaches, and weight gain. Most resolve over about 3 months as your body gets used to them.

Other Resources:

The Guttmacher Institute
1301 Connecticut Avenue, NW
Suite 700
Washington, DC 20036
Phone: (877) 823-0262
Fax: (202) 223-5756
Web Address:

The American College of Obstetricians and Gynecologists
409 12th Street, SW
PO Box 96920
Washington, DC 20090-6920
Phone: (202) 638-5577
Fax: (202) 484-5107
Web Address:

American Medical Association
515 North State Street
Chicago, IL 60610
Phone: (800) 621-8335
Web Address:

Association for Reproductive Health Professionals
2401 Pennsylvania Avenue, NW
Suite 350
Washington, DC 20037-1718
Fax: (202) 466-3825
Web Address:

Centers for Disease Control and Prevention
1600 Clifton Road
Atlanta, GA 30333
Phone: (800) 311-3435
Web Address:

Institute for Reproductive Health
Georgetown University
4301 Connecticut Avenue, NW
Suite 310
Washington, DC 20008
Phone: (202) 687-1392
Fax: (202) 537-7450
Web Address:

U.S. National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894
Phone: (888) 346-3656
Web Address:

National Women's Health Network
514 10th Street, NW
Suite 400
Washington, DC 20004
Phone: (202) 628-7814
Fax: (202) 347-1168
Web Address:

National Women's Health Information Center
U.S. Department of Health and Human Services
Office on Women's Health
Phone: (800) 994-9662
Web Address:

National Women's Health Resource Center
157 Broad Street
Suite 315
Red Bank, NJ 07701
Phone: (877) 986-9472
Web Address:

North American Menopause Society
PO Box 94527
Cleveland, OH 44101
Phone: (440) 442-7550
Fax: (440) 442-2660
Web Address:

Planned Parenthood Federation of America
434 West 33rd Street
New York, NY 10001
Phone: (800) 230-7526
Fax: (212) 245-1845
Web Address:

Debra Ravasia, updated 2017