Birth Control Pills: Side Effects and Complications

Woman taking birth control pill
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While most women who use birth control pills don't experience any problems, oral contraception may cause side effects and risks—as well as benefits. Common side effects range from bleeding between periods, irregular menstruation, and water retention, to breast tenderness and mood changes. And while it is also relatively uncommon, women over 35 who smoke are more likely to get blood clots while on "the pill," as it's called.

Common Side Effects

There are a range of common side effects associated with birth control pills. These include:

Consult your doctor if these don't subside after two or three months. He/she may switch you to another birth control pill.

Rare Side Effects

Generally speaking, a healthy woman who doesn’t smoke is unlikely to experience serious side effects from oral contraceptives. That said, the hormones in birth control pills can pose some risks for some women.

More serious side effects from birth control pills may include:

  • Blood clots
  • Liver tumors
  • Heart attack
  • Cancer
  • Stroke

In rare cases, birth control pills can be life-threatening.

Overall, birth control bills do not appear to significantly increase a woman's risk of cancer. However, evidence has found that the risks of breast and cervical cancers are increased in women who use oral contraceptives, but the risks of endometrial, ovarian, and colorectal cancers are actually decreased. 

Breast cancer: There is some evidence that women may have a slightly higher risk of breast cancer due to the hormones estrogen and progestin found in birth control pills. A large 2017 study found that overall, women who were currently taking oral contraceptives, or recently stopped taking them, had a 20% increase in the relative risk of breast cancer when compared to women that never used oral contraceptives. (A relative risk is used when comparing two groups, in this case, oral contraceptive users versus non-users.) The study also found that longer oral contraceptive use was associated with increased risk of breast cancer. 

Higher concern does exist for some women who have:

Cervical cancer: Women who have consistently used oral contraceptives for five or more years have a greater risk of developing cervical cancer than women who have never used oral contrceptives. The longer oral contraceptives are used, the risk of cervical cancer increases. But fortunately, risk of cervical cancer has been found to decrease over time after use of pills stops.

Stroke: A 2015 review of 24 observational studies determined that the risk of ischemic stroke was increased for oral contraceptive users when compared to non-users. The researchers also found an increased risk of (ischemic) stroke with increasing amounts of estrogen found in oral contraceptives.

Complications

Skipping your pill for one day will increase your risk for pregnancy.

Sometimes, breakthrough bleeding can indicate an underlying medical condition. Light spotting is less concerning than heavy or continuous breakthrough bleeding, in which case you should consult your doctor. Record when you bleed, how much you bleed, and how long it lasts. These details can help diagnose the cause of your bleeding.

Once you begin to use the pill, you should have your blood pressure checked. If your blood pressure can be successfully managed (either through diet and exercise or medication), your doctor will most likely allow you to continue your pill use.

Smoking and birth control pills can be a bad combination. If you’re a smoker and over 35, combination oral contraceptives should not be used. Instead, smokers are often prescribed progestin-only pills. Combination oral contraceptives should also be avoided if you've had a heart attack, stroke, blood clots, or liver tumors.

When talking with your doctor about oral contraceptives, be sure to tell her/him any medications you're taking and any prior medical problems.

When to See a Doctor/Go to the Hospital

If you experience any of the following symptoms, contact your doctor immediately. These may be symptoms of a blot clot:

  • Leg swelling
  • Leg pain
  • Redness of skin
  • Irregular heartbeat
  • Shortness of breath or difficulty breathing
  • Chest pain
  • Coughing up blood
  • Lightheadedness/fainting
  • Low blood pressure

A Word From Verywell

While the side effects explained in this article speak to the potential negative impacts associated with birth control pills, there are also benefits to taking oral contraceptives. These include milder menstrual cramps, lighter periods, improved acne, and protection against certain types of breast disease, ovarian cysts, anemia, and perhaps uterine and endometrial cancer.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. MedlinePlus. Estrogen and progestin (oral contraceptives). Updated September 15, 2015.

  2. National Cancer Institute. Oral contraceptives and cancer risk. Updated February 22, 2018.

  3. Centers for Disease Control and Prevention. What are the risk factors for breast cancer? Updated September 11, 2018.

  4. Harvard Health Publishing. New guidelines aim to help women prevent stroke. Updated March 14, 2014.

  5. Planned Parenthood. How safe is the birth control pill?

  6. Centers for Disease Control and Prevention. Know the risks, signs & symptoms of blood clots. Updated February 7, 2020.

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