Birth Control Pills: Side Effects and Complications

Birth control pills may cause side effects like bleeding between periods, irregular menstruation, and mood changes. Most people who take birth control pills, however, don't experience side effects. When side effects do happen they tend to go away after a few months of use.

While it is also relatively uncommon, people over 35 who smoke are more likely to get blood clots while taking birth control pills.

This article discusses the side effects of birth control pills and when to see a healthcare provider.

Woman taking birth control pill
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Common Side Effects

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

Consult your healthcare provider if these don't subside after two or three months. They may switch you to another birth control pill.

Rare Side Effects

Generally speaking, a healthy person 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 people. In rare cases, birth control pills can be life-threatening.

More serious side effects from birth control pills may include:

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

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

Breast Cancer

There is some evidence that people 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, people 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 those who 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 people who have:

Cervical Cancer

People who have consistently used oral contraceptives for five or more years have a greater risk of developing cervical cancer than people with a cervix who have never used oral contraceptives.

The longer oral contraceptives are used, the risk of cervical cancer increases. But fortunately, the risk of cervical cancer has been found to decrease over time after the use of pills stops.


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.


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 healthcare provider.

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 healthcare provider 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 healthcare provider about oral contraceptives, be sure to tell them about any medications you're taking and any prior medical problems.

When to Seek Emergency Care

If you experience any of the following symptoms, contact your healthcare provider 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.

6 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).

  2. National Cancer Institute. Oral contraceptives and cancer risk.

  3. Centers for Disease Control and Prevention. What are the risk factors for breast cancer?

  4. Harvard Health Publishing. New guidelines aim to help women prevent stroke.

  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.

By Tracee Cornforth
Tracee Cornforth is a freelance writer who covers menstruation, menstrual disorders, and other women's health issues.