What Are 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.)

How to Get Them

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

Your healthcare provider may or may not require a pelvic exam and Pap smear in order to prescribe the birth control pill. Some healthcare providers 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 healthcare provider 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.

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.

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:

• Desogestrel
• Ethynodiol Diacetate
• Levonorgestrel
• Norethindrone
• Norethindrone Acetate
• Norgestimate
• Norgestrel
• Drospirenone

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

Additional Benefits of Combination Pills

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).