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Birth Control Pills (Combined Oral Contraceptives)

Birth Control Pills (Combined Oral Contraceptives)

What are birth control pills?

oral contraceptive pillBirth control pills (also known as combined oral contraception or “the pill”) are used to prevent pregnancy.  They are an effective non-surgical and reversible method of contraception.  If taken consistently and correctly, birth control pills are more than 99% effective in preventing pregnancy. However, it can be difficult to remember to take a pill every day, and about 9% of women become pregnant while taking the pill each year.

Most birth control pills contain synthetic forms of two hormones—estrogen and progestin—that are naturally found in the body.  These “combination” hormone pills prevent ovulation and also create thick cervical mucus that helps keep sperm from entering the uterus.  Pills do not protect you from sexually transmitted diseases.

Progestin-only contraceptives are birth control pills that only contain one of the two hormones.  This article is about combination pills.

Birth control pills do not provide protection against STDs.

Who can use the pill?

Birth control pills are generally safe and effective for most healthy people.  A careful medical evaluation is required before the pill is prescribed.  If you have any of the following conditions, be sure to mention them to your provider, because special attention may be required:

  • Personal or family history of strokes
  • Personal or family history of blood clots
  • Diabetes
  • Cancer
  • High blood pressure
  • Gallbladder disease
  • Migraine headaches

Using tobacco products significantly increases the risk of harmful side effects, so be sure to talk to your doctor about your tobacco use.  Hall Health can offer you help in quitting smoking.

What are the benefits of using the pill?

  • Excellent protection against pregnancy (less than 2 to 9 pregnancies per 100 women each year)
  • Periods are generally lighter, shorter, less painful, and more regular
  • Helps with acne
  • Helps with premenstrual symptoms (PMS) such as headaches and depression

The pill offers many other benefits, including some protection against:

  • Cancer of the uterus (in women who have taken the pill in the past)
  • Cancer of the ovaries (in women who have taken the pill in the past)
  • Benign breast cysts (while taking the pill)
  • Benign ovarian cysts (while taking the pill)
  • Certain kinds of anemia
  • Bone thinning
  • Pelvic inflammatory disease (PID)

What are side effects and risks of using the pill?

Side effects

The following symptoms can occur when one starts taking the pill.  They are usually mild and go away sometime during the first few months of taking the pill.  If they do not stop or if they become too bothersome, talk to your provider about changing the way you take the pill or the kind of pill you take.

  • Bleeding between periods or so-called “breakthrough bleeding”
  • Nausea
  • Breast tenderness
  • Mood changes
  • Skin changes
    • Acne may improve or worsen
    • Rarely darkening of skin over cheeks, which may be permanent
  • Weight changes
  • Mild headaches
  • Changes in sexual desire

Those taking birth control continuously may experience breakthrough bleeding for the first six months.

After stopping the pill, it can take up to six months for your period to return to the way it was before you started taking contraceptives.


The rare but serious side effects (those that can result in death, serious illness or disability) of birth control can include:

  • Blood clots
  • Strokes
  • Benign liver tumors (an extremely rare condition)

These complications occur rarely in young, healthy, nonsmoking women, especially among those who take low-dose pills. But since they are serious, is important to be aware of the possibility and the warning signs that could suggest such a condition is developing.  The risk of blood clots with the pill is much lower than the risk in pregnancy.

Contact your doctor or local emergency room if you experience any of the following, because they could be a sign of a blood clot, heart attack or stroke:

  • Severe headache
  • Visual changes (flashing lights in the eyes, blurring and/or partial loss of vision)
  • Numbness or tingling in the face, an arm, leg, hand or foot
  • Pain in the chest, shortness of breath, or coughing up blood (these symptoms may indicate possible clots in the lungs)
  • Severe leg pain (possible clot in the leg)
  • Crushing chest pain or heaviness
  • Severe abdominal pain

Other considerations

If you are ill or need medical care, be sure to tell your health care practitioner you are taking the pill.  Know the name and dosage of the pill you use.  If surgery is anticipated, it may be advisable to discontinue the pill one month before the operation. Please discuss this with your surgeon.

Certain medications (including antibiotics, anticonvulsants, herbals) make the pill less effective.  If another medication is prescribed for you while you are taking the pill, talk with your practitioner and your pharmacist about possible drug interactions.

How do I take the pill?

Instruction for use may vary slightly from one brand to another.  You should read and follow the instructions that come with your pill.  With all brands of pills, it is recommended that you:

  • Take your pills as close to the same time each day as possible.  Try not to vary the time that you take your pill by more than two hours.
  • Use a back-up birth control method for the first seven days after you start the pill.
  • Once you start using the pill, don’t stop taking it unless either your practitioner advises you to stop, or you let your practitioner know you want to stop.

What do I do if I miss a pill?

If you’ve been taking a birth control pill with estrogen and progestin for at least seven days, use the following table to determine what you need to do.  You should consider taking emergency contraception (the morning after pill) if you have unprotected sex and have missed pills.

Number of pills missed

When pills missed

What to do…

Seven day back up method (condoms) needed?

First 1-2 pills Beginning of pack Take the missed pill as soon as it is remembered and the next pill at its regular time.  This means you may take two pills in one day. Yes
1-2 pills Anytime between Day 3 and Day 21, provided you’ve been on birth control for more than 7 days Take the two pills on the day you remember.  Then take one pill a day until you finish the pack.  This means you may take two pills in one day. No
3 or more pills First two weeks Take the two pills on the day you remember.  Then take one pill a day until you finish the pack. This means you may take two pills in one day. Yes
3 or more pills Third weeks Do not finish the pack, and throw away the remaining pills.  Start the next pack. Yes
1-7 reminder pills Fourth week Throw away the remaining reminder pill(s) and take the next pill at the usual time. No


Additional resources provides information about many different birth control methods

Planned Parenthood’s website offers information on the effectiveness of different kinds of birth control methods

If you have any questions and are a UW student or established Hall Health patient, you may call one of our Consulting Nurses for further information.


Authored by: Hall Health Center Women’s Health Clinic staff

Reviewed by: Hall Health Center Women’s Health Clinic staff, January 2014