top of page

Most oral contraceptives, commonly called "the pill," contain a combination of estrogen and progestin. The combination pill reduces the risk of pregnancy by:

  • Preventing ovulation

  • Keeping the mucus in the cervix thick and impenetrable to sperm

  • Keeping the lining of the uterus thin

The pill makes menstrual bleeding more regular, with fewer days of flow and overall lighter flow. Other benefits of the pill include a reduction in:

  • Menstrual cramps or pain

  • Risk of ovarian cancer or cancer of the endometrium (uterine lining)

  • Acne

  • Iron-deficiency anemia (a low blood count due to low iron levels)


One potential downside of the pill is that in order to maximize efficacy, you have to remember to take it every day, ideally at the same time of day. Some women find this difficult or inconvenient.

Side Effects:

The most common side effects of this medicine include nausea, stomach pain, headache, weight gain, and breast pain. If these bother you or appear serious, let your doctor know. There may be ways of reducing or preventing them. Consult your doctor if you frequently experience spotting or brown discharge in the middle of the cycle. You must also consult your doctor if you notice unexplained swelling and pain in your limbs, shortness of breath, chest pain or changes in vision.

Do not continue with the medicine and consult with the doctor if your periods do not start within a week of the treatment. Your doctor should also know about all other medicines you are taking as many of these may make this medicine less effective or change the way it works. Avoid the use of medicine if you are pregnant or breastfeeding.

Efficacy — When taken properly, birth control pills are a highly effective form of contraception; however, skipping pills or forgetting to restart the pill after the week of your period will decrease efficacy. Approximately 9 out of every 100 women who take birth control pills for one year will have an unintended pregnancy.

Missed pills are a common cause of pregnancy. In general, if you forget to take an active pill (containing hormones), you should take it as soon as possible and take the next one at the usual time it is due. If you miss more than two pills, use a backup method of birth control (eg, condoms) for seven days.

Side effects — Possible side effects of the pill include:

  • Nausea, breast tenderness, bloating, and mood changes – These typically improve within two to three months without treatment.

  • Bleeding between periods – Irregular bleeding, also called "breakthrough bleeding" or "spotting," is particularly common during the first few months of taking the pill. It almost always resolves without any treatment within two to three months. Forgetting a pill can also cause breakthrough bleeding.

Taking birth control pills does not cause weight gain.

If you are taking the pill, tell your health care provider right away if you experience abdominal pain, chest pain, severe headaches, eye problems, or severe leg pain. These could be symptoms of several serious conditions including heart attack, blood clot, stroke, and liver or gallbladder disease.

Potential complications — When the pill was first introduced in the 1960s, the doses of both hormones (estrogen and progestin) were quite high. Because of this, cardiovascular complications occurred, such as high blood pressure, heart attacks, strokes, and blood clots in the legs and lungs.

The pills prescribed today have much lower doses of progestin and estrogen, which has decreased the risk of these complications. As a result, birth control pills are now considered a reliable and safe option for most healthy, nonsmoking women. While there is a very small risk of blood clots, this risk is actually lower than the risk in pregnant women or those who have recently given birth.

Experts have studied the possible association between taking the pill and the risk of breast cancer. While these studies have had mixed results, there is some evidence that women who take the pill do have a slightly higher risk of getting breast cancer later in life than women who do not. However, if there is an increase in risk, it is very small, especially in younger women. It's important to balance this against the benefits of the pill, which include not only pregnancy prevention but a reduction in the risk of ovarian and endometrial cancer (see above).

Who should not take the pill? — Because of an increased risk of complications, you should not take the pill if you:

  • Are 35 or older and smoke cigarettes (as this puts you at high risk for cardiovascular complications such as blood clots or heart attack)

  • Are pregnant

  • Have had blood clots or a stroke in the past (as this increases your risk of blood clots while taking the pill)

  • Have a history of an "estrogen-dependent" tumor (eg, breast or uterine cancer)

  • Have abnormal or unexplained menstrual bleeding (in which case the cause of the bleeding should be investigated before starting the pill)

  • Have active liver disease (the pill could worsen the liver disease)

  • Have migraine headaches associated with certain visual or other neurologic symptoms (eg, aura), which increases your risk of stroke


Some women may take the pill under certain circumstances, but need close monitoring. Talk with your doctor or nurse if you:

  • Have high blood pressure – You may experience a further increase in blood pressure and should be monitored more frequently while on the pill.

  • Take certain medication for seizures (epilepsy) – In this case, the pill may be slightly less effective in preventing pregnancy because the seizure medicines change the way it is metabolized.

  • Have diabetes mellitus – Women with diabetes and kidney disease or vascular complications from diabetes should not use the pill.

Antibiotics — Rifampin, which is sometimes used to treat tuberculosis, can decrease the efficacy of hormonal birth control. As a result, women who take rifampin are advised to avoid most hormonal birth control methods, with the exception of depo-medroxyprogesterone acetate (Depo-Provera).


Other alternative options include an intrauterine device (IUD), condoms, or a diaphragm, or sterilization.

Contrary to popular belief, other (more commonly used) antibiotics do not affect the efficacy of hormonal birth control methods. Backup contraception is not needed when you take these antibiotics.

Starting the pill — Ideally, you should start taking the pill on the first day of your period. This provides protection from pregnancy beginning immediately.

As long as you are sure you are not pregnant (which can be confirmed with a urine pregnancy test), it is also an option to start the pill as soon as your doctor prescribes it, regardless of where you are in your menstrual cycle. This is called the "quick start" method. If you do this, you will need to use a backup form of birth control (eg, condoms) for the first seven days after the quick start.

Many women start taking the pill on the first Sunday after their period starts (because most pill packs are arranged for a Sunday start). If you do this, you will also need to use some form of backup contraception (eg, condoms) for the first seven days after the Sunday start.


When to expect a period — Traditionally, the pill is taken on a 28-day cycle that includes 21 days of hormone pills followed by 7 days of placebo pills ("sugar pills") that do not contain hormones. Newer formulations have a longer duration of hormone pills (eg, 24 days) and fewer days of placebo pills (eg, 4 days). It is not necessary to take the placebo pills, as they do not contain any active ingredients, but many women find it easier to stay on schedule when they continue to take a daily pill throughout the entire 28-day cycle.


Your period should arrive during the fourth week of the pill pack (ie, the week that you are taking placebo pills or no pills). However, some women have irregular breakthrough bleeding or spotting in the first few months.

Continuous dosing — Some women prefer to take hormone-containing birth control pills continuously, without the week of no pills or placebo pills. This allows you to control whether and when you have a monthly period. This regimen often works well for women with painful periods, endometriosis (a condition that causes abdominal pain), or bothersome premenstrual symptoms, including mood changes.

Traditional birth control pill packs can be used in continuous dosing. To do this, you take the first three weeks of a pill pack, then immediately start a new pack the next day (without taking a break or taking the placebo pills). This can be continued for as long as desired.

Over time, using continuous-dosing regimens results in fewer periods per year (or no periods at all); however, many women experience breakthrough bleeding when starting a continuous-dosing regimen. Breakthrough bleeding is inconvenient, but does not mean that the pills are less effective (assuming you are taking them at the same time each day and not skipping any active pills).

Progestin-only pills — Some pills contain only progestin (sometimes called the "mini pill"); these may be an option for women who cannot or should not take estrogen. This includes women who are breastfeeding or who have worsened migraines or high blood pressure with combination contraceptive pills. Progestin-only pills are as effective as combination pills when taken at the same time every day, but have a slightly higher failure rate if you are more than three hours late in taking it. A backup method of birth control should be used for seven days if you forget a pill or are more than three hours late in taking it.

Progestin-only pills are taken on a 28-day cycle, and all 28 pills contain hormone (ie, there is no "placebo week"). Breakthrough bleeding or spotting is common with progestin-only pills.



We understand our duty to help you understand birth control pills better

Please review the information below

bottom of page