Monophasic birth control pills are a form of contraception. They contain equal amounts of the hormones estrogen and progestin for an entire monthly cycle.

For more than 50 years, birth control pills have given women the peace of mind of knowing that they won’t get pregnant until they are ready for a baby. Around 82 percent of women who use contraception have used the pill, according to a report from the Centers for Disease Control and Prevention (CDC).

The birth control pill has come a long way in those last 50 years, and there are many different options for women who use the pill for birth control. In this article, we take a look at monophasic pills specifically.

Monophasic birth control pills in round pack.Share on Pinterest
Monophasic birth control pills may be used to regulate the menstrual cycle and to treat PCOS, although they are mainly used to prevent pregnancy.

One of the most common types of birth control pill is the combination pill. This type of pill contains both progestin and estrogen.

These two hormones work in several ways to prevent pregnancy:

  • by stopping ovulation or the release of a mature egg
  • by thickening cervical mucus, making it harder for sperm to get past
  • by thinning the lining of the uterus, making implantation of an egg harder

The amount of estrogen and the kind of progestin is different in each brand and type of pill. Most pills have either 20 or 35 micrograms (mcg) of estrogen. There are different types of combination pills, depending on the quantity of hormones in each pack.

Monophasic pills have the same amount of estrogen and progestin throughout the entire month of pills.

Monophasic birth control pills are mostly used to prevent pregnancy in women who are sexually active, but there are many other uses as well. Some women, such as those with polycystic ovary syndrome (PCOS), use the pill to help regulate their menstrual cycles.

Also, the pill can improve menstrual cycle symptoms by:

  • reducing cramps and pain
  • lightening bleeding
  • easing premenstrual syndrome (PMS)

Medically, the use of the birth control pill may also improve bone density and bone health, and reduce the risk of ovarian and uterine cancer.

Multiphasic pills

In contrast to monophasic pills, multiphasic pills have varying amounts of estrogen and progestin in the pack of pills.

The most common type of multiphasic pills is triphasic, meaning that there are three different doses of estrogen in the pill pack.

This type of pill follows the changing hormone levels during a woman’s menstrual cycle more closely.

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Some people may find that they experience fewer side effects when taking monophasic birth control pills, compared with combined pills.

Monophasic pills come in either 21-day or 28-day pill packs. In both cases, these types of pills have the same amount of hormones for 21 days.

  • Women taking the 21-day formulation would take 21 days of active hormones, followed by 1 week of not taking pills.
  • Women taking the 28-day formulation would also take the 21 days of active hormones plus 7 days of placebo pills.

This 7-day break from active hormones is the time that a woman would have her period.

Monophasic pills are the most commonly prescribed type of birth control. There are many brands of monophasic pills, all having estrogen (ethinyl estradiol) and a variety of progestin formulas.

This table lists various progestin combinations with examples of a brand name:

ProgestinEstrogenBrand name examples
levonorgestrelethinyl estradiolAlesse, Aviane, Levlite, Levora, Nordette
desogestrelethinyl estradiolApri, Desogen, Ortho-Cept
norethindroneethinyl estradiolBrevicon, Ortho-Novum, Modicon, Necon, Norinyl, Nortrel, Ovcon, Tri-Norinyl
ethynodiol diacetateethinyl estradiolDemulen, Zovia, Kelnor
norethindrone acetateethinyl estradiolLoestrin, Microgestin
norgestrelethinyl estradiolLo-Ovral, Ovral
drospirenoneethinyl estradiolYasmin
norgestimateethinyl estradiolOrtho-Cyclen

A woman should keep in mind that some of these brands also make triphasic or biphasic pills with the same brand name.

People should always talk to their doctor if they have any medication questions or concerns.

Everyone’s body reacts differently to the birth control pill. Some women experience fewer side effects when taking the monophasic pill because they are taking a steady level of hormones in their pill.

Also, women taking combination pills may have lighter periods with fewer cramps. Some types of pill have been associated with reduced acne.

Research has also shown that combination pills can reduce the risk of certain types of cancers, such as ovarian and endometrial.

Monophasic birth control pills are the most commonly prescribed and studied. This means that they have the most amount of research supporting their safety and efficacy. It does not mean, however, that this type of birth control is better, safer, or more effective than the other brands or types.

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A doctor or pharmacist can discuss the potential side effects of different types of birth control pills.

The side effects of monophasic birth control pills are the same as other types of birth control pills. They may include:

  • spotting or bleeding between periods
  • possible weight gain
  • nausea
  • mood changes or depression
  • breast tenderness

These symptoms are not usually anything to be concerned about, but it is always best for someone to discuss them with their doctor to be sure.

Birth control pills have also been linked with some serious medical conditions. Anyone experiencing any of the following side effects while taking the pill should contact their doctor immediately:

  • blurred vision
  • severe chest or abdominal pain
  • severe headache
  • pain or swelling in the legs

If the symptoms occur after-hours, someone should go to the nearest emergency room. These symptoms could signal the presence of a blood clot that can cause a stroke or heart attack.

Without prompt treatment, very serious complications or even death can occur.

While using a monophasic birth control pill is usually safe, some women should not use the pill.

Women over the age of 35 years old, women who smoke, or women who have a history of previous blood clots should not use monophasic pills.

Before using the pill, women should also be warned about their risk for blood clots or other complications if they have any of the following medical conditions:

Women who are breast-feeding should not take the combination birth control pill because of the risk that the estrogen in the pill can reduce milk production and supply. Lactating women who wish to use hormonal birth control should consider using a progestin-only pill to avoid this concern.

In addition, certain medications may not be as effective if taken with a birth control. Medications that may interact with the birth control pill include:

  • some antibiotics or antifungals
  • anti-seizure drugs
  • anti-HIV drugs
  • St. John’s Wort

Women taking these drugs should be sure to mention it to their doctor and may want or need to use another form of birth control.

The monophasic birth control pill is a very safe and effective option for many women. When used correctly, it is 91–99 percent effective in preventing pregnancy.

It may take experimenting with a few different brands before the right pill is found, so it is important to stay in touch with the doctor and report any side effects.