What Are Combination Birth Control Pills?

Estrogen Doses, Progestin Types, and Added Benefits of the Pill

Young woman holding birth control pills
What do you need to know about the different types of combination birth control pills?. PhotoAlto/Ale Ventura/PhotoAlto Agency RF Collections/Getty Images

What are combination birth control pills (oral contraceptives) and what are the differences between the multitude of different prescription products? What are some of the advantages and disadvantages of the different options?

Definition of Combination Birth Control Pills

Combination birth control pills are oral contraceptives that combine synthetic estrogen (ethinyl estradiol) and progestin, similar to the natural sex hormones (estrogen and progesterone) produced in a woman's body. Combination birth control pills may also be referred to as "combo pills" or simply, "the pill."

Unlike estrogen (the synthetic preparation ethinyl estradiol) which is found in various brands of combination pills, there are several different types of progestin which may be used (discussed below.)

Obtaining Combination Birth Control Pills

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

Your doctor may or may not require a pelvic exam and Pap smear in order to prescribe the birth control pill. Some doctors will prescribe combo pills on the basis of careful medical history and blood pressure measurement (as the pill can increase blood pressure.) Even if your doctor does not require a Pap smear when prescribing the pill, it's important to have Pap smears every three years between the ages of 21 and menopause, and more often if you have had an abnormal Pap smear or positive HPV test.

Before you see your doctor, check out these ideas on how to talk to your doctor about birth control and the questions you should ask.

  • 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.
      • Monophasic pills have the same amount of estrogen and progestin in each of the active pills in the pack.
    • Biphasic pills change the level of estrogen and progestin one time during the active pills, with the level of progestin increasing in the second half of the cycle.
    • Triphasic pills change the levels of hormones three times during the cycle, and both the estrogen and progestin level may change.

    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.
    • 28-Day Packs

      In a 28-day 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 every day. Therefore, a woman will take a pill each day during the 4-week cycle.
    • 21-Day Packs

      In a 21-day 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 people fewer hormone fluctuations than the traditional 21 days of active pills per 28-day cycle. (See the warning, however, about Yasmin and Yaz 28 below.)
    • Loestrin 24 Fe: Approved by the FDA in 2006, this 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. Popular brands include:
      • 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 2003. This regimen allows women to have fewer 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 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 less estrogen and progestin than Seasonique.
    • 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 enjoy 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.
    • Menstruation

      When using combination birth control pills, women usually will have withdrawal bleeding (a 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 in the Combination Pill

      • All combination pills contain estrogen (typically ethinyl estradiol) and a specific type of progestin designed to mimic the natural hormone progesterone. These progestins include:
        1. Desogestrel
    • Ethynodiol Diacetate
    • Levonorgestrel
    • Norethindrone
    • Norethindrone Acetate
    • Norgestimate
    • Norgestrel
    • Drospirenone
    • You may wish to learn more about the role of progestin in the pill and why some types of progestin may meet your needs better than another.
      • A Warning About Yasmin and Yaz 28

        Unlike other combination birth control pills, Yasmin an Yaz 28 contain the progestin drospirenone which may increase potassium levels, and this increase in potassium could potentially cause serious heart-related or 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 may increase the risk of blood clots.
      • Estrogen Dosages in the PIll

        Ethinyl estradiol is the type of synthetic estrogen found in oral contraceptives. The higher the amount of estrogen in the pill (the higher the number of micrograms of ethinyl estradiol) means the greater the effects of estrogen on your body (both good and bad.)
      • Low-Dose Combination Pills

        Low-dose combination pills contain the lowest amount of estrogen (20 mcg) plus one of the types of progestin. Brand names of this type of pill include:
        • Alesse
      • Aviane-28
      • Levlite
      • Loestrin 1/20
      • Mircette

      Regular-Dose Combination Pills

      Regular dose 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

      Phasic combination pills have changing levels of estrogen and progestin designed 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

      High-dose 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

      Combination Pills With Additional Purposes

      The primary purpose of birth control pills is, of course, to prevent pregnancy. Yet there are some brands and combinations of hormones which may pack an extra punch, and help with other concerns as well. In other words, there are some noncontraceptive benefits of the pill which vary between brands.
      • Some of the conditions for which the pill may help (and is sometimes approved for as well) include acne, premenstrual dysphoric disorder, endometriosis, and painful periods. In addition, the pill may help lower your risk of uterine, ovarian, colon and blood-related cancers, though there may be an increased risk of lung cancer in people who smoke and breast and cervical cancers in current users of the pill (the increased risk appears to go away within five years of stopping the pill.)
      • Starting the Pill

        If you are just starting the pill, it can be helpful to read up on some of the basic things you need to know to use the pill effectively. You may also have questions about exactly how the pill works.
      • When taking the pill, it's also important to be aware of what medications may lower the pill's effectiveness. For example, many people are unaware that taking an antibiotic for a bladder infection may significantly decrease the effectiveness of the pill—and increase the chance that you become pregnant.
      • Changing Your Birth Control Pill

        There are many different pills to choose from, but it's important to talk to your doctor about how to switch birth control pills if you do so.
      • Comparison of Combination Pills 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 combination pill. For those who have these concerns, such as elevated blood pressure on a combination pill, a progestin-only pill may be a good option.
      • Bottom Line on Combination Birth Control Pills

        In wading through the information above, you've probably noticed that there are many variables to consider in choosing the right pill for yourself. The type of estrogen in pills is the same (ethinyl estradiol) but the dosage can vary. Estrogen can have both positive and negative effects in the body, and the right dose for you will depend on your own wishes and your medical history.
      • Unlike estrogen, there are several different types of progestins which may be used. Each of these may have both benefits (such as the control of acne) or risks (such as the risk of blood clots) and it's important to talk to your doctor about which progestin might be best for you as an individual.
      • The beauty of having so many different combinations of pills is that there are many other options to choose from if one type leads to side effects. At the same time, it's important to talk to your doctor about how to switch birth control pills if you do so.
      • The pill is very effective when used properly, and can even kill the proverbial two birds with one stone for some people with premenstrual syndrome, acne, menstrual migraines, and other conditions. That said, it is most effective in all of these capacities when used carefully so that pills aren't missed and if you talk to your doctor promptly about any side effects or worries.
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