Oral contraceptives

Oral contraceptives
Last update: 27-10-2023

How else can it be called?

  • Contraceptive pills

  • Birth control pills

What are oral contraceptives?

Oral contraceptives, commonly known as birth control pills, are medications designed to prevent pregnancy. They may consist of either progesterone alone or a combination of estrogen and progesterone, hormones akin to those naturally produced in the ovaries.

Over the years, the dosage of estrogen in oral contraceptives has been lowered to minimize the risk of circulatory diseases. However, there remains a potential risk, especially for women who smoke, which can further increase the likelihood of such complications.

There are two main types of oral contraceptives available:

  • The "Combined Pill": Contains a combination of estrogen and progesterone.
  • The "Mini Pill": Contains only progesterone at very low doses.

What is the effectiveness of combined oral contraceptive pills?

Combined oral contraceptive pills are remarkably effective, with a pregnancy rate of less than 1 per 100 women per year, making them a highly reliable choice for birth control.

Adherence to the instructions provided in the leaflet is crucial, as the effectiveness of these contraceptives significantly diminishes if not taken as directed. Missing three or more pills or delaying the start of the next pack by three or more days substantially lowers their efficacy, resulting in a rate of 7 pregnancies per 100 women per year in such cases.

It is essential to note that oral contraceptives come in different formats. Some consist of 21 tablets, taken for 21 days followed by a 7-day break before starting the next pack. Others contain 28 tablets, taken continuously without any breaks.

If you happen to miss a pill for a day or two, you can take two pills the following day and then resume your regular dosage of one pill per day.

If you miss the pills for several consecutive days, it's advisable to use additional support methods such as sexual abstinence, barrier methods, or properly executed interrupted intercourse until the start of the next cycle.

Consider emergency planning if there are any concerns.

Can all women take the combined pill?

There is an absolute contraindication to taking the combined pill (estrogen plus progesterone), or any other contraceptive method containing estrogen, in the following cases:

  • First six months after giving birth while exclusively breastfeeding.
  • First six months after childbirth without breastfeeding, but with a risk of deep vein thrombosis (clot formation in the leg veins, potentially leading to pulmonary thromboembolism). Risk factors include cesarean delivery, blood transfusion during childbirth, obesity, prolonged bed rest, and a history of these clots.
  • Women over 35 years of age who smoke.
  • Severe liver diseases: cirrhosis, tumors, active viral hepatitis.
  • Uncontrolled high blood pressure.
  • Diabetes for more than twenty years or with kidney, eye or nerve complications.
  • Gallbladder disease.
  • History of thrombosis, embolism or heart attack.
  • History of breast cancer.
  • History of migraines with aura (bright lights with loss of vision in one eye before the headache).
  • Taking specific anticonvulsant medications and certain tuberculosis medications.
  • Major scheduled surgery requiring complete rest for more than a week.
  • Any disease that increases the risk of clot formation (excessive clotting).

Women who do not exactly meet these criteria but are close to these diagnoses should be evaluated with caution.

The age of the woman should always be considered when prescribing hormonal contraceptives.

In theory, any healthy woman without a personal or family history of risks can use any hormonal method until she reaches menopause (complete cessation of menstruation). However, it is crucial for the woman and her doctor to make this decision together.

What is the mini pill?

The minipill is a hormonal contraceptive method suitable for women with contraindications to estrogen use, particularly following childbirth.

They are highly effective for breastfeeding women, with a success rate of less than 1 pregnancy per 100 women per year.

If the woman does not breastfeed or has her period, the effectiveness decreases to 7 pregnancies per 100 women per year.

Minipills are available in packages of 28 and 35 tablets that are taken every day without interruption.

If you miss one or two doses, you can take two in one day and continue with the pack without any interruption.

If you miss three or more doses, it's recommended to use additional support methods such as barriers, sexual abstinence, or properly executed interrupted intercourse until you resume taking the pills consistently, which could be within a week. If there are any doubts, considering emergency contraceptives is advisable.

Absolute contraindications for using the mini pill or any other planning method containing progesterone include:

  • History of liver cirrhosis or severe liver tumor
  • History of deep vein thrombosis or pulmonary thromboembolism
  • History of breast cancer
  • Taking specific anticonvulsant medications and some tuberculosis medications

What side effects could they have?

Oral contraceptives may have certain side effects that are important to be aware of:

  • The combined pill (or any pill containing estrogen)

    Particularly in the early stages, the pill may lead to irregular bleeding or breakthrough bleeding.

    There are many birth control pills available in the market and it is up to your doctor to decide which one is the most appropriate.

    Some women experience regular periods while taking the pill and may cease menstruating when they discontinue its use. This effect is typically temporary.

    Approximately 5% of women using oral contraceptives may observe a slight increase in blood pressure after approximately 5 years of use.

    Other possible side effects include nausea, mild headache, breast tenderness, fluid retention, depression, and nervousness. Moreover, weight gain might occur, attributed either to fluid retention or an increased appetite induced by the pill, leading to consuming more food.

  • The minipill (pill with progesterone)

    The effects are similar, leading to more irregular periods and, in some cases, the complete absence of menstruation.

Are there any positive effects?

Oral contraceptives also offer positive effects.

While taking the pill, menstruation is typically less painful with fewer cramps, reduced breast swelling, and a decreased risk of anemia or iron deficiency. Additionally, there is a lower risk of developing ovarian cysts, ovarian or endometrial cancer, and rheumatoid arthritis.

It also reduces the risk of pelvic inflammatory disease and is used to treat hirsutism (excessive hair growth) and other symptoms of Polycystic Ovary Syndrome.

Your menstrual cycles will become more regular, consistent, and predictable.

Medically reviewed by Yolanda Patricia Gómez González Ph.D. on 27-10-2023


  • A Practical Guide to Obstetrics & Gynecology (1st Ed) 2015, Richa Saxena, ISBN: 978-93-5152-479-3, Pag. 365.
  • World Health Organization Department of Sexual and Reproductive Health and Research (WHO/SRH) and Johns Hopkins Bloomberg School of Public Health/Center for Communication Programs (CCP), Knowledge SUCCESS. Family Planning: A Global Handbook for Providers (2022 update) Baltimore and Geneva: CCP and WHO; 2022. Available on:

Rating Overview

Share your thoughts about this content

E-mail (Optional):
Add a review