Medically reviewed by Deborah Weatherspoon, Ph.D., R.N., CRNA — created by Rachel Nall, MSN, CRNA top top January 28, 2020

Birth control pills space a popular and effective method of contraception. However, part factors, together as missing pill days, vomiting, and taking details medications, deserve to reduce the performance of the pill and also may an outcome in unintended pregnancies.

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In this article, us look at how effective the birth control pill is, and also five reasons why the pill could fail. We additionally give advice on exactly how to prevent pill failure and describe some early signs of pregnancy.

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The merged pill consists of hormones that stop ovulation, which is as soon as the ovaries relax an egg for fertilization. Another kind of pill, known as the minipill, causes a who cervical rubber to thicken and also the uterine lining come thin, which reduces the likelihood the sperm getting to an egg.

The birth regulate pill is an extremely effective if a human being takes that correctly and also does not miss any pill days. Follow to the Centers for an illness Control and also Prevention (CDC), the pill is 99.7 percent effective with perfect use. This means that less than 1 the end of 100 women who take the pill would become pregnant in 1 year.

However, with usual use, the performance of the pill is 91 percent. This way that around 9 out of 100 ladies would come to be pregnant in a year of taking the pill.

Five reasons for pill failure

Although the birth manage pill is generally very effective, some instances can mitigate its effectiveness and also may sometimes an outcome in unintentional pregnancies. This include:

Missing a day

Manufacturers intend for civilization to take it the pill everyday for it come be many effective. If a human being misses a day, their hormone levels might not continue to be at regular enough levels to protect against pregnancy.

If a human being finds it an overwhelming to take the pill top top a daily basis, other birth control methods may better suit their needs. A medical professional or gynecologist can advise top top the variety of alternative contraceptives.


Sometimes a human may it is in ill when they take the pill. As soon as a human being vomits, the pill can come ago up, or they might not totally absorb it right into their body.

Anyone who experiences vomiting quickly after acquisition the pill must take another pill as quickly as possible and then take their next pill together usual.

Not acquisition the pills in ~ the exact same time each day.

In addition to taking birth control pills daily, a human being should likewise take the pills at roughly the exact same time every day. This can maintain your hormone levels more consistently.

A person should constantly take the minipill in ~ the exact same 3-hour time home window every day. Someone who misses their home window should usage a backup birth control an approach for the next 2 days or avoid having sex.

Many people set a daily alarm remind them come take their pill at the correct time every day.

Not starting a brand-new pack right away

It is important to start a brand-new pack of pills the day after finishing the ahead one. However, periodically a human being may not have actually their brand-new package yet. Lacking a couple of days between packs have the right to make the pill less efficient at preventing pregnancy.

According come the CDC, anyone that misses 2 or much more pills in a row must use a backup contraceptive technique or avoid sexual intercourse till they have taken the birth control pill because that 7 continually days.

Medications the interfere v the pill

Some medications can make the pill much less effective. Drugs include particular antibiotics, such as rifampicin, and anti-fungal drugs, such together griseofulvin.

A human being should use back-up contraception while acquisition these medications and for 48 hours after finishing the course.

Other more long-term medications and supplements may also impact how well birth manage pills work. These have the right to include:

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Birth manage pills are an extremely effective if a human being takes lock correctly and also does not miss any kind of pill days. The complying with tips can aid prevent unintended pregnancies while taking the pill:

reading the packaging and following the accuse carefullytaking the pill at the exact same time every dayalways getting a new pill pack at least 1 week before the last pill pack is as result of run outalways acquisition missed pills as quickly as possibleusing a backup technique of contraception, such together a condom, if a human being misses taking two or an ext pills in a row

If a human being is concerned about not gift able to take your pills consistently, they should speak to their doctor or gynecologist around other birth regulate methods. Over there are several options available that carry out not require taking a pill daily, such together an intrauterine device, or IUD.

If a human being is concerned about contraceptive failure and also the possibility of being pregnant, they must speak to your doctor. However, over there are also some beforehand signs that have the right to indicate pregnancy:

Bloating. If bloating is often a symptom of premenstrual syndrome, it have the right to sometimes additionally be a authorize of at an early stage pregnancy.Light spotting. A tiny amount the bleeding or spotting can take place when an egg attaches come the uterine lining. If spotting occurs external of an intended menstrual cycle, it might be an early symptom of pregnancy.Unexplained fatigue. Hormonal transforms that take place in the body during pregnancy can make a person feel tired, even during the at an early stage stages.Urinating more often. Hormonal alters can rise a woman’s have to urinate during early pregnancy.

Anyone that thinks they might be pregnant might wish to take it an at-home pregnant test. These tests have actually become an ext sensitive come a person’s hormone levels and far better at detecting pregnancy in its more quickly stages.

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However, at-home pregnant tests still may not reputable if an separation, personal, instance takes that too early or does not follow the accuse correctly. According to the United says Food and Drugs management (FDA), for most reliable results, a human being should take the test 1–2 weeks after their very first missed period.