Combination Pills

Combination pills, also called “combo pills,” contain a combination of the hormones estrogen and progestinthat prevent pregnancy by inhibitingovulation, thickening the cervical mucus, or changing the endometrial lining of the uterus

How Combination Pills Work

A 21-day pack contains 21 pills that are all active pills, which means they all contain hormones.One pill is taken each day and then no pills are taken for the last seven days.Bleeding typically occurs once per month, during the days in which no active pills are taken.2

Another method is called the continuous or extended method, which is designed to reduce the number of menstrual periods per year.1Most continuous-pill packs have 84 active pills in a row (about three months’ worth of pills), followed by seven inactive pills. Bleeding occurs during the seven days during which the inactive pills are taken, resulting in only four periods per year. There are also pill formulations that can be taken year round, eliminating menstrual bleeding altogether.2

There are many variations of pill packs for both the conventional method and the continuous method. They all contain different amounts of hormones that protect against pregnancy every day. With monophasic formulations, each active pill contains the same amount of estrogen and progestin; with biphasic and triphasic formulations, the amount of hormones in each pill varies as the pack goes on.Every female is different and will find that some methods and variations will work better than others.

What They Are and What They Do

The progestin and estrogen in combination pills work together to prevent pregnancy by thickening cervical mucus so that sperm cannot pass through the cervix and into the uterus or fallopian tubes to fertilize an egg. These hormones also suppress ovulation (the release of an egg from the ovaries) and change the lining of the uterus to further prevent pregnancy by inhibiting implantation of an egg.1

How Combination Pills Should Be Taken

A female can begin to take the pill at any time once she has had her first menstrual period.If a pill pack is started within five days after the start of the menstrual period, it is called a “first-day start.” A “Sunday start” involves taking the first pill of a pack the Sunday following a menstrual period. A “quick start” is when the first pill is taken immediately, regardless of the current phase of the menstrual cycle.For a first-day start, the pill will begin working right away, so it would be a good idea to use a backup contraceptive (such as a male condom) for at least a week after starting the pill. If the pack is started at any other time during the menstrual cycle, as with a Sunday start or a quick start, it will not reach effectiveness for about a week. A backup contraceptive should be used for the first seven days after starting the pill to avoid pregnancy.1

The pill can be taken right after an abortion or miscarriage. It is best to wait at least three weeks after giving birth to start taking the combo pill. If a female has just given birth and is breastfeeding, she should wait six weeks before taking the pill because the estrogen it contains can inhibit milk production and cause harm to a developing infant.1

Because the hormones in the pill can cause unfortunate side effects such as weight gain, nausea, and moodiness, it is generally recommended that females take the lowest dose of hormones possible. This method allows the pill to protect against pregnancy with little to no side effects.A doctor will be able to recommend the appropriate amount of hormones for each specific female.

What to Do If You Miss a Pill

It is strongly recommended that a backup birth control method (such as a condom) be used for at least seven days following a missed pill to prevent pregnancy. This may be more important for some types of pills than others, depending on the amount of hormones in the pill. If you have unprotected sex at any time during the seven days following a missed pill, consider using emergency contraception.Most pill packs will come with specific instructions for what to do if you miss a pill, but in general, you can follow the instructions below.

Here are some instructions for conventional method users:

• If you miss any number of active pills during week one of the cycle, take one active pill as soon as you remember and continue the rest of the pack as usual; this means that you may have to take two pills in one day.

• If you miss one or two active pills during week two or three of the cycle, take one active pill as soon as you remember and continue the pack as usual until the end of the third week. Start a new pack at the end of week three instead of taking a hormone-free week. You may experience bleeding, but continue to take the active pills.

• If you miss three or more pills during week two or three of your cycle, take one active pill as soon as you remember and continue to take the rest of the pack as usual. At the end of week three, discard any placebo pills and start a new pack immediately. It is especially important to use a backup birth control method if you miss any pills during this time. 

• If you miss any inactive pills during week four, throw the missed pills away. There is actually no need to take these pills anyway, as they are just reminders. But remember to start a new pack of pills no more than seven days after your last active pill.3

Here are some instructions for continuous or extended method users:

• If you miss any pills on day one through 21, follow the instructions for the conventional method above.

• You can miss up to seven active pills in a row after day 21,but you should never go more than seven days without taking any hormones, as this will greatly increase the risk of pregnancy.

• If you miss more than seven active pills after day 21, take one active pill as soon as you remember and continue the pack as usual, and remember to use a backup method of birth control.

Combination Pills vs. Progestin-Only Pills

You should not take the combination pill if you match any of the following descriptions:

• Are older than 35 and smoke cigarettes

• Get frequent migraine headaches

• Have blood clotting disorders or are being treated for blood clots

• Have had a heart attack, stroke, angina, or other serious heart problem

• Have lupus

• Have liver disease or liver cancer

• Have diabetes

• Have uncontrollable high blood pressure

• Are or will be on bed rest for a prolonged period of time1

All of these risk factors may be caused or worsened by the estrogen in combination pills. Do not take the combination pill if you are breastfeeding, as the estrogen in the pills can interfere with milk production. If any of these health restrictions apply to you, you may want to consider other types of contraception, such as the progestin-only birth control pill.Progestin-only pills do not contain estrogen, and therefore do not have the severe side effects associated with taking the combination pill. However, progestin-only pills are much more time-sensitive and do not carry some of the advantages that combination pills do. It is best to talk with your doctor or clinician about which pill best accommodates your needs.

Effectiveness of Combination Pills

The effectiveness of the combination pill depends on multiple factors. The largest factor is the regularity with which the pill is taken. “Perfect use” means that the pill is taken every day, exactly as directed, with no mistakes or missed pills—thus, the perfect-use failure rate is quite low. “Typical use” is a slightly more realistic description of how users will take the pill, which accounts for periodic mistakes or missed pills. The combination pill has a failure rate of 1% when females are “perfect” users. This means that one oral contraceptive user out of 100 will become pregnant within one year if the pill is used exactly as instructed. The failure rate among “typical” users is 9%, meaning that nine oral contraceptive users out of 100 will become pregnant within one year under typical conditions. In addition, the pill may be less effective for females who are overweight or who are experiencing vomiting and diarrhea. Certain medications, such as antibiotics, HIV medications, and anti-seizure medications can also reduce the effectiveness of the pill. Using the pill in conjunction with a barrier contraceptive, such as the female condom or male condom, can further reduce the chances of fertilization.1

Using birth control pills alone does NOT protect against the transmission of sexually transmitted infections (STI's). To reduce the risk of contracting and spreading STI's, always use a condom and get tested.

Here are some advantages and disadvantages associated with the use of combination pills:


• Combination pills can significantly reduce menstrual cramps and premenstrual syndrome (PMS) symptoms, such as headaches, menstrual migraines, irritability and depression.

• The estrogen in the pills regulates periods and can make them lighter and/or shorter.

• Many females experience reduced acne and an increase in breast size.

• Along with its ability to protect against pregnancy,the pill can protect against many health problems, including pelvic inflammatory disease, bone thinning, ectopic pregnancy, endometrial and ovarian cancers, infection of the fallopian tubes, ovaries, and uterus, iron-deficiency anemia, cysts in the breasts or ovaries, uterine fibroids, and breast tumors (both benign and cancerous).1

• Should you decide that you want to become pregnant, you can stop taking the pill at any time. The pill is immediately reversible, which means that you could become pregnant right away; for most women, however, fertility does not completely return to normal until after about two weeks of pill discontinuation.

• When using continuous or extended cycle pills, there are fewer periods per year.

• Continuous cycle pills can also provide relief from the pain of endometriosis.2

• You can skip the placebo pills and continue to take active pills for up to three (sometimes four) months if you wish to have fewer periods. This is especially convenient for people who travel frequently. Discuss this with your doctor before trying it.

• Oral contraceptives allow for sexual spontaneity.


• The pill does not protect against STI's.

• The combination pill is somewhat time sensitive;it must be taken every day for maximum protection against pregnancy.

• The pills have side effects such as bleeding or spotting between periods (this is even more common with continuous cycle pills), breast tenderness, nausea, vomiting, mood changes and/or depression, weight gain and increase in breast size, and headaches (these will usually clear up within two to three months).

• The hormones in the pill may lower sexual desire.

• It can take anywhere between one to six months for periods to become regular after stopping the pill, though it is possible to become pregnant immediately after stopping.1

• There is a slight possibility of developing blood clots. The possibility of this happening is very rare and is most likely to occur in cases wherein someone is immobilized or confined to a bed.

• Some pills have a higher risk for blood clots and associated health problems than others, so it is a good idea to talk to a doctor about your pill regime and its associated health risks.1

• Certain prescription medications or antibiotics can decrease the effectiveness of the pill. You should speak to your doctor to see if any prescriptions or supplements you may be taking could interfere with the pill. If the medication you are taking is one that decreases the effectiveness of the pill, you should abstain from intercourse or use a backup method of birth control, such as a condom, until you are no longer on that medication.

• The pill typically requires a prescription from a doctor or a visit to a clinic.

Whether or not the advantages of the combination pill outweigh the disadvantages, or vice versa, is dependent upon each individual’s body and their needs. So again, consulting a doctor to discuss which birth control method may be appropriate before making a decision is highly encouraged.

Potential Side Effects

It is important to see a doctor if any one of the side effects mentioned earlier persists or worsens in any way. More serious side effects are rare but can happen. They may include any of the following.

If you experience any of the following, consult your doctor immediately:

• Heart attack or stroke

• Blood clots in the legs, lungs, heart, or brain

• High blood pressure

• Liver tumors

• Gallstones

• Jaundice

• New lumps in the breasts

• A sudden, severe headache that worsens or happens more often than usual

• Achy soreness in the leg

• Aura

• Chest or abdominal pain

• A sudden missed period after a serious of regular periods

• Difficulty breathing

• Yellowing of the skin or eyes

• Depression

• Blurred Vision

• Fainting

• Severe skin rash

• Seizure

The pill has been said to increase the risk of breast cancer in some females. However, most recent medical literature suggests that the pill has little to no effect on the increased risk of developing breast cancer. In fact, the pill may help to prevent breast cancer along with endometrial and ovarian cancer.1

Concluding Remarks

The combination pill is a useful alternative to progestin-only or estrogen-only birth control pills. Anyone considering which method of birth control is best for them should always consult with their doctor before making a decision. There are many other options in the realm of female birth control beyond oral contraception to consider as well. For more information about the various types of birth control, click here!



1. "Birth Control Pills." Planned Parenthood, n.d. Web. 17 Apr. 2014. <

2. "Combination Birth Control Pills." Mayo Clinic, n.d. Web. 18 Apr. 2014. <

3. "The Pill." McKinley Health Center, University of Illinois, n.d. Web. 18 Apr. 2014. <>.

Last Updated 31 May 2019.