Oral Contraceptive Pills (OCP): What You Should Know

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Oral contraceptive pills (OCP), most commonly known as "the pill," are a popular birth control method. Some people take OCP to prevent pregnancy, and when taken correctly, it is up to 99% effective. However, it is important to note that the pill doesn't protect you from sexually transmitted diseases (STDs), including HIV.

In this article, we will look at the types of OCP, factors that influence effectiveness, benefits, side effects, and costs.

Birth control pills

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There are two types of OCP:

  • Combination pills contain the hormones estrogen and progestin. These are the most common type of birth control pill in the U.S.
  • Progestin-only pills (also known as the minipill) which contain progestin only

Estrogen and progesterone stop your ovaries from releasing eggs and thin the lining of the womb, so there is less chance of a fertilized egg implanting into the womb and being able to grow.

The minipill uses only progestin (a synthetic version of the hormone progesterone). It works mostly by causing changes that keep sperm from reaching eggs.


If taken correctly, birth control pills are very effective in preventing pregnancy. Both the combination pill and the progestin-only pill have 9% failure rates with typical use. That means out of 100 women using the pill, 9 would get pregnant. With perfect use as directed, the pregnancy rate is less than 1 in 100 women every year.

To be fully effective, progestin pills must be taken within the same three-hour time period every day.

In general, you should try to take combination pills at the same time each day, but you can take them within the same daily 12-hour window and still be protected.

Certain medications may make either type of pill less effective. These include:

  • Rifampin (an antibiotic)
  • Drugs that are used to treat human immunodeficiency virus (HIV) infection, such as darunavir, efavirenz, cobicistat, lopinavir/ritonavir, and nevirapine, may interact with birth control.
  • Barbiturate medicines that are prescribed for treating insomnia, controlling anxiety, or treating seizures (such as phenobarbital).
  • Anti-seizure medicines such as carbamazepine, felbamate, oxcarbazepine, phenytoin, primidone, and topiramate
  • St. John’s wort
  • Emend (aprepitant), which is used to prevent or treat nausea and vomiting, can interfere with the effectiveness of oral contraceptives.

Excessive vomiting and/or diarrhea can also lower the effectiveness of the pill. If you are experiencing these symptoms, contact your healthcare provider for advice about additional methods of birth control.

While oral contraceptives are very effective for lowering pregnancy risk, no oral contraceptive will protect you from sexually transmitted diseases.


There are many benefits to taking the pill:

  • They may make your period more regular, lighter, and shorter.
  • They help reduce menstrual cramps.
  • They decrease the risk of cancer of the uterus, ovary, and colon.
  • They may improve acne and reduce unwanted hair growth.
  • They can be used to treat certain disorders that cause heavy bleeding and menstrual pain, such as fibroids and endometriosis.

Noncontraceptive Benefits

Combination birth control pills that include both estrogen and progestin can also provide health benefits. They may offer you some protection against:


A small percentage of women who take the combination (estrogen-containing) birth control pill have an increased risk for developing these rare complications:

Your healthcare provider will talk to you about your level of risk based on your medical history. Luckily, if an individual is not able to use an estrogen-containing pill, most can still safely take progestin-only pills.

Side Effects

If you use birth control pills, you may experience some unwelcome side effects. The good news is that most of these side effects will go away by the second or third month of use as your body adjusts to the hormones in the pill.

Birth control pill side effects may include:

  • Headaches
  • Breast tenderness
  • Nausea (sometimes with vomiting)
  • Spotting or bleeding between periods
  • Higher risk of blood clots and high blood pressure

Progestin-only birth control pills may lead to irregular spotting and bleeding (at least, more frequently than with combination pills).

If you experience side effects that are long-lasting and disruptive, speak to your doctor as there are many different versions of OCP that you can try. If you stop taking the pill suddenly, it will no longer offer protection against pregnancy so you will need to use an alternative method of birth control.


Prices vary depending on whether you have health insurance, or if you qualify for Medicaid or other government programs that cover the cost of birth control pills. For most brands, one pill pack lasts for one month, and each pack can cost anywhere from $15-$50. With most health insurance plans, birth control may be totally covered or there might be a copay. If you qualify for some government programs, the cost may also be covered.

You may also need to pay for an appointment with a healthcare provider to get a prescription for the pill. This visit can cost anywhere from $35–$250. While the Affordable Care Act (Obamacare) guarantees coverage for most women with health insurance, the details can vary from state to state and plan to plan.

If you’re worried about cost, your local Planned Parenthood will be able to help you find options to suit your budget.


Taking the oral contraceptive pill can not only prevent pregnancy but also offer a range of benefits such as lighter periods and reduced menstrual cramps. If you have any side effects your doctor may be able to prescribe a different pill or an alternative form of birth control.

A Word From Verywell

The oral contraceptive pill is a safe, effective way to prevent pregnancy. But to be at their most effective, you need to remember to take them around the same time every day. Many people find setting a daily alarm on their cell phones to be a good reminder. Talk to your healthcare provider if you think the pill is the right choice for you.

Frequently Asked Questions

  • What is OCP birth control?

    Oral contraceptives (birth control pills) are hormone-containing medications that are taken by mouth to prevent pregnancy. 

  • How reliable is OCP birth control?

    If taken exactly as directed, OCP birth control is 99% effective. That figure drops to 91% if the medication is not taken as directed.

  • Where do I get OCP birth control?

    You need a prescription for birth control pills. You can get a prescription from a doctor or nurse at a doctor’s office, health clinic, or your local Planned Parenthood health center.

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4 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. Planned Parenthood. Are birth control pills effective?

  2. Office on Women's Health. Birth control methods. Updated April 24, 2017.

  3. The American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 110: noncontraceptive uses of hormonal contraceptivesObstet Gynecol. 2010;115(1):206-218. doi:10.1097/AOG.0b013e3181cb50b5

  4. Cleveland Clinic. Birth control: the pill. Updated July 21, 2020.