What Are Combination Birth Control Pills?

Young woman holding birth control pills
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Definition of Combination Birth Control Pills

Combination birth control pills are oral contraceptives that combine synthetic estrogen and progestin, similar to the natural sex hormones (estrogen and progesterone) produced in a woman's body.

Unlike estrogen, several types of progestin can be found in various brands of combination pills. Read more about Understanding Progestin in Combination Birth Control Pills.

Available by Prescription Only

All combination birth control pills are available only by prescription. This means you cannot buy any of these pills over the counter.

Your doctor might or might not require a pelvic exam and pap smear in order to prescribe these pills. Some doctors will prescribe combo pills on the basis of careful medical history and blood pressure measurement.

Talk to your doctor first to find out what he/she requires to write a pill prescription.

    Combination Birth Control Pills Are Also Known As

    • The pill
    • Combo pills
    • Combination pills

    Types of Combination Birth Control Pills

    Combination birth control pills are categorized as monophasic, biphasic, or triphasic depending on whether the level of hormones stays the same during the first three weeks of the menstrual cycle or if it changes.

    Combination Birth Control Pack Size

    Combination birth control pills typically come in a one-month supply.

    Combination pills are usually available in either 28-day or 21-day packs.

    Both versions have 21 active pills. These are the pills that include the hormones that prevent a woman from becoming pregnant. Read more about Choosing the Right Combination Birth Control Pill.

    28-Day Packs

    In this type of pack, the last seven pills are known as reminder pills.

    They do not contain any hormones. These pills are taken during the fourth week, and their purpose is to help the woman maintain her routine of taking a pill everyday. Therefore, a woman will take a pill each day during the 4-week cycle.

    21-Day Packs

    In this type of pack, the pills are taken for the first three weeks, and a woman takes nothing during the fourth week. She will start a new pack of pills eight days after the previous pack is completed. An example of a pill brand that comes in a 21-Day pack is Loestrin. These pill packs can be tricky because women need to remember to start their new pill pack without any reminder pills.

    24-Day Packs

    There are two combination birth control pill brands that have 24 active days and only four placebo pills. These include:

    • Yaz 28 (and Beyaz): The dosage regimen of Yaz is unique in that it contains 24 days of hormone pills, followed by 4 reminder-day pills. This option might offer patients fewer hormone fluctuations than the traditional 21 days of active pills per 28-day cycle. See the Warning About Yasmin and Yaz 28, below.
    • Loestrin 24 Fe: Approved by the FDA in February 2006, the pill brand was the first 24-day oral contraceptive approved in the US.

      Extended Cycle Pills

      Extended cycle combination pills (also known as continuous cycle pills) have more pills in each pack. These pills can allow you to completely skip your period or lower the frequency of your period. Studies show that extended cycle pills are safe. They also can be convenient and improve the quality of life for many women who suffer from menstrual-related problems. Here are popular brands:

      • Seasonale is a continuous dosage pill that contains ethinyl estradiol/levonorgestrel. It can be taken continuously for 91 days and was FDA approved for routine contraception in September 2003. This regimen allows women to have less menstrual periods per year. This pill pack has 84 active pills and 7 placebo pills.
      • Seasonique is another continuous dosage combination birth control pill that was approved by the FDA in May 2006. Seasonique is similar to Seasonale in that ethinyl estradiol/levonorgestrel is taken continuously for 84 days. With Seasonique, however, the final 7 days of the 3-month cycle contain low-dose ethinyl estradiol rather than placebo tablets.
      • LoSeasonique also is available. This formulation has lower amounts of both estrogen and progestin.
      • Lybrel is a low-dose continuous birth control pill. It is taken all 365 days of the year. In May 2007, it was the first pill FDA approved to be used to completely stop a woman's monthly period. Many women who use Lybrel love not having their periods but share varying experiences with this pill brand.

      Women can check their pill package insert to find out exactly which hormones are present and at what dosages throughout the cycle.


      When using combination birth control pills, women usually will have withdrawal bleeding (her period) during the fourth week. The hormones contained in the active pills prevent pregnancy throughout the month, so even during the fourth week (regardless if she is taking reminder pills or no pills at all), a woman is protected against becoming pregnant.

        Progestin Hormones

        All combination pills contain estrogen (typically ethinyl estradiol) and a specific type of progestin, designed to mimic the natural hormone of progesterone. These progestins include:

        1. Desogestrel
        2. Ethynodiol Diacetate
        3. Levonorgestrel
        4. Norethindrone
        5. Norethindrone Acetate
        6. Norgestimate
        7. Norgestrel
        8. Drospirenone

        A Warning About Yasmin and Yaz 28

        Unlike other combination birth control pills, these two brands contain the progestin drospirenone, which may increase potassium levels that could cause serious heart and other problems. These pills might not be the right method for you if you have ever had kidney, liver, or adrenal gland disease. There is also some concern that drospirenone-containing combination birth control pills may pose an increased risk of developing blood clots.

        Estrogen Dosages

        Ethinyl estradiol is the type of synthetic estrogen found in oral contraceptives. The higher the number of micrograms of ethinyl estradiol leads to more potent effects of estrogen.

        Low-Dose Combination Pills

        These pills contain the lowest amount of estrogen (20 mcg) plus one of the types of progestin. Brand names of this type of pill include:

        Regular-Dose Combination Pills

        These pills contain 30 to 35 mcg estrogen plus one of the types of progestin. Brand names of this type of pill include:

        • Brevicon
        • Demulen 1/35
        • Desogen
        • Femcon Fe
        • Levlen
        • Lo/Ovral
        • Modicon
        • Nordette
        • Levora
        • Loestrin
        • Low-Ogestrel
        • Necon 1/35
        • Norinyl 1/35
        • Ortho-Cept
        • Ortho-Cyclen
        • Ortho-Novum 1/35
        • Ortho Tri-Cyclen Lo
        • Ovcon 35
        • Seasonale
        • Yasmin
        • Zovia 1/35E

        Phasic Combination Pills

        These pills have changing levels of estrogen and progestin to more closely mimic the hormonal phases during a woman’s menstrual cycle. Brand names of this type of pill include:

        • Ortho Tri-Cyclen Lo
        • Jenest-28
        • Ortho Tri-Cyclen
        • Cyclessa
        • Triphasil
        • Tri-Levlen
        • Ortho-Novum 10/11
        • Trivora
        • Tri-Norinyl
        • Estrostep Fe
        • Ortho-Novum 7/7/7

        High-Dose Combination Pills

        These combination pills have around 50 mcg of estrogen plus progestin. Brand names of this type of pill include:

        • Ortho-Novum 1/50
        • Ovral
        • Demulen 1/50
        • Ogestrel
        • Ovcon 50

        Common Questions About Combination Birth Control Pills

        Comparison to Progestin-Only Pills

        The combination birth control pill is slightly more effective than the progestin-only pill. Yet some women's bodies do not react well to the estrogen in the combo pill, so it may be better for them to use the progestin-only pill.

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