What is the contraceptive pill? – Efficacy, how to take it and risks

By (embryologist), (gynecologist), (gynecologist) and (embryologist).
Last Update: 04/26/2022

Oral contraceptives, generally known as the birth control pill, contraceptive pill or "the pill", are a very reliable hormonal method to prevent unwanted pregnancy. Since it was approved in the United States in the 1960s, its use has been increasing and it is currently one of the most widely used contraceptive methods worldwide. It was marketed in Spain in 1978.

The contraceptive pill is taken orally on a regular basis and is usually combined, i.e. it is composed mainly of two hormones: an estrogen and a progestin.

There are many brands of oral contraceptives available, although all of them would work in a similar way. The following indications are general, so it is advisable to consult with your gynecologist before starting to take them and to read the information leaflet carefully.

Provided below is an index with the 10 points we are going to expand on in this article.

what is the pill and how does it work?

The combined oral pill is a hormonal contraceptive method that contains an estrogen and a progestin in its composition. This contraceptive must be prescribed by a gynecologist, who must previously verify that there is no contraindication for its use. The contraceptive pill prevents unwanted pregnancy in several ways:

It is important to note that the combined oral contraceptive pill has the disadvantage that it does not protect against sexually transmitted diseases(STDs). For this, a barrier contraceptive such as a condom should be used.

how effective is the pill?

The contraceptive pill is a very reliable method to prevent unwanted pregnancies and its effectiveness has been estimated at 99% with perfect use and 91% with regular use.

The effectiveness of the pill depends on its correct use without forgetfulness. In addition, there are other factors that can interfere and reduce the effectiveness of the pill. Among them are:

  • Vomiting and diarrhea. If the woman has vomiting or diarrhea shortly after taking the contraceptive pill (within the first 3-4 hours), the situation is similar to forgetfulness. A new tablet must be taken within 12 hours, except if it was a placebo pill.
  • St. John's wort. Preparations with this herb are sometimes used for depression, but may reduce the effectiveness of the contraceptive pill.
  • Some drugs, for example, to treat epilepsy, tuberculosis and infections such as HIV or hepatitis C.

Therefore, when taking other medications or herbs, it is imperative to consult a specialist if a condom should be used due to a possible reduction in the effectiveness of the contraceptive pill.

How should the pill be taken?

In order for the hormones administered when taking the pill to exert their effect on the hypothalamus-pituitary-ovary axis (responsible for regulating the menstrual cycle), it is important to take the pill correctly, without forgetting to do so.

In addition, the contraceptive pill should be taken at approximately the same time each day. For this reason, it is often very useful to set a reminder alarm on the cell phone.

On the other hand, there are two main types of contraceptive pill blister packs:

  • Blister of 21 tablets: 21 tablets with active ingredient are included. In this case, the woman will have a week's break between one blister pack and the next during which she will not take any pills.
  • Blister of 28 pills: includes 21 pills with active ingredient (estrogen and progestin) and 7 placebo pills (without hormones). The purpose of taking these tablets without active ingredient is that the woman does not lose continuity between one blister pack and the next, in order to avoid forgetfulness.

In any case, contraceptive pill packaging often simulates a calendar. This makes it easier for the woman to keep track of the pills she has taken and helps her not to forget to take any.

If the contraceptive pill is being used correctly, it will always coincide with starting a new pack on the same day of the week (i.e., always on a Monday every 28 days). In addition, there will also be menstrual-like vaginal bleeding on the same day of the week, every 28 days, on day 2-3 of rest or placebo.

What happens if I forget to take my birth control pill?

First of all, it should be noted that the following is a general procedure to follow in the event of forgetting to take the contraceptive pill. It is always advisable to consult the specific information leaflet of the pill the woman is using.

If the woman forgets to take a tablet at the exact time and takes it before the 12-hour delay, there would still be contraceptive efficacy, so there would be no risk of pregnancy. To do so, take the tablet at the time you remember (within those 12 hours) and continue with the rest of the pills as usual.

On the other hand, if more than 12 hours have passed since the tablet should have been taken, contraceptive efficacy may be affected. There is an increased risk of pregnancy if a pill is missed at the beginning of the pack or near the rest or placebo week.

Therefore, different actions should be taken depending on when the forgetfulness occurred.

Week 1

If the forgetfulness occurs in week 1, the woman should take the pill the moment she realizes it, even if it is followed by the next one. The remaining tablets in the package should be taken as usual. However, it is recommended to use a condom if sexual intercourse takes place during the following 7 days.

On the other hand, if sexual intercourse had taken place in the week prior to forgetting, the woman should consult a specialist before taking the pill again, as it is possible that she could be pregnant. In the meantime, condoms should be used if sexual intercourse takes place.

Week 2

If the forgotten contraceptive pill corresponds to week 2, you should act in the same way as in week 1.

However, if all the pills had been taken correctly in the 7 days prior to forgetting, it is not necessary to use an additional contraceptive method.

Week 3

In the case that the forgotten pill corresponds to week 3, one of these two indications should be followed:

  • Take the tablet as soon as possible, even if this means taking two tablets at a time. Subsequently, the rest of the pills will continue to be taken as usual. However, the rest or placebo week should not be carried out, but the next blister pack of tablets should be started immediately. Since there is no rest week or placebo week between packs, there will be no menstruation, but it is possible to have slight leaks or small spotting.
  • Stop taking the tablets in the initiated blister pack and complete a maximum of 7 days without taking any tablets (including the day of forgetfulness). Once this is done, a new blister pack will be started. It is possible to shorten the 7 pill-free days, if the woman wishes to start the new blister pack on the usual day of the week.

If the tablets had been taken correctly during the 7 days prior to forgetting, by adopting one of these options it will not be necessary to use another contraceptive.

Week 4

If a contraceptive pill is missed in week 4, it means that the woman is using a pill that comes in packs of 28 pills, the last 7 being a placebo.

Therefore, a forgetfulness of these pills (which usually have a different color) will not have any relevance in contraceptive protection. In this way, the woman should continue with the next tablets as usual, without the need to take the forgotten placebo pill.

Side effects and risks of the Pill

Some side effects may occur when taking the contraceptive pill. However, not all women have them and, moreover, they may disappear in a few months. Otherwise, if these adverse effects persist, it is advisable to consult a specialist so that he/she can prescribe a different pill.

Among the adverse effects of the contraceptive pill are the following:

  • Headache.
  • Breast Sensitivity and discomfort
  • Depressed mood, mood swings, irritability.
  • Dizziness.
  • Nausea and vomiting
  • Diarrhea
  • Weakness, tiredness.
  • Weight gain.
  • Vaginal bleeding.

In addition, one of the most important risks of combined hormonal contraceptives is the increased risk of venous or arterial blood clots. This is why the specialist must check that there is no history and risk factors for this complication before prescribing this type of contraceptive.

For all these reasons, when taking the contraceptive pill, it is important to attend the regular check-ups prescribed by the gynecologist.

What is the mini-pill?

It is a pill that, unlike combined oral contraceptives, only contains progesterone as the active ingredient. It is therefore a good alternative for women who want to or must avoid estrogens for medical reasons.

In this case, the minipill is taken daily and continuously, i.e. without a rest period or placebo period between packs. In addition, it is even more important for this type of pill that it is always taken at the same time.

FAQs from users

Can long-term use of hormonal contraceptives cause infertility?

By Sergio Rogel Cayetano M.D. (gynecologist).

Many patients ask this question when they come for consultation. The answer is no, contraceptives cannot diminish the ability to have offspring in the medium and long term.

A woman's ovary has from birth a number of follicles (structures of the ovary that contain the egg inside). Some of these follicles are recruited monthly to compete with each other. The most prepared and developed follicle will be the one selected so that the egg inside it will be released in the middle of the cycle with the intention of being fertilized. The rest of the follicles that were recruited that month, simply degenerate.

Imagen: contraceptive-pill-infertility

In the case of contraceptives, their administration will prevent the most evolved follicle from maturing and releasing the egg to the outside, so that all the follicles recruited will be lost and degenerate.

This means that contraceptives do not influence the ovarian reserve or fertility of the woman under treatment.

It is possible that after stopping contraceptive treatment, a woman may experience menstrual imbalances or amenorrhea. This is because her hypothalamic-pituitary-ovarian hormonal axis has been suppressed for a long time and it takes a few months for it to return to normal functioning. Perhaps, this fact is what fuels the belief that contraceptives decrease fertility or ovarian reserve in women who have been using them for a long time.
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When does the contraceptive pill start to be effective?

By Júlia Roig Navarro M.D. (gynecologist).

If started on the first day of menstrual bleeding, the contraceptive pill is effective from that very moment. This is because follicular growth and ovulation will not occur and the endometrium will not be receptive.

Imagen: onset-of-contraceptive-pill-effectiveness

It must be taken every day at the same time and, if taken correctly, it is more than 99% effective.

Many women forget to take it during the first months, which is why some professionals recommend the additional use of a condom. In this way, in addition to avoiding pregnancy, we will reduce the risk of contracting sexually transmitted diseases.

What are the advantages and disadvantages of the contraceptive pill?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

The main advantages of the contraceptive pill are that it is a reliable, practical and reversible method of contraception when a woman wishes to become pregnant. In addition, the pill can have beneficial effects such as reducing the risk of certain types of cancer.

On the other hand, the disadvantages of combined oral contraceptives include the fact that it requires monitoring to avoid forgetfulness and that it can have some serious side effects and risks. In addition, this contraceptive method does not protect against STDs.
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When is the contraceptive pill contraindicated?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

In general, the contraceptive pill should not be taken if the woman has:

  • Blood clots, heart attack or stroke (or history).
  • Blood clotting disorders.
  • Diabetes.
  • High blood pressure.
  • Liver disease or tumor (or history).
  • Elevated cholesterol or triglyceride levels.
  • Hyperhomocysteinemia.
  • Cancer of the breast, ovary, cervix or uterus (or history).
  • Unexplained vaginal bleeding.
  • Migraine with aura (or history).
  • Pancreatitis (or history).

Likewise, it would also be contraindicated if the woman is going to undergo an operation or spends too much time without being on her feet.

During the pill rest period should I use a condom?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

No, it is not necessary as long as all the hormone-containing tablets have been taken correctly. This means that if the contraceptive pill is used correctly, the woman maintains contraceptive efficacy in the rest or placebo period and therefore does not need to use a barrier method of contraception.

However, it is important to remember that the contraceptive pill does not protect against sexually transmitted diseases (STDs). For this reason, condoms should be used in any sexual intercourse where there is a risk of STDs.

What to do if you forget several birth control pills?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

In the event that more than one contraceptive pill has been missed, it is advisable to consult a specialist on how to proceed.

However, in any case, a barrier method of contraception should be used, since the contraceptive efficacy of the pill will have been lost.

What is the price of the contraceptive pill?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

The price of the contraceptive pill can vary between 5 and 20 euros. However, its price may depend on whether or not it is financed by the Social Security (in which case it may be cheaper).

In any case, the contraceptive pill should always be purchased at the pharmacy with a doctor's prescription.

Suggested for you

If you are interested in reading more information about other contraceptive methods, you can visit the following link: Contraceptive methods: types, effectiveness, risks and prices.

On the other hand, we have already mentioned that the contraceptive pill does not protect against STDs. If you want to know more about this, I recommend you read this article: Sexually Transmitted Diseases (STDs) in men and women.

We make a great effort to provide you with the highest quality information.

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FAQs from users: 'Can long-term use of hormonal contraceptives cause infertility?', 'When does the contraceptive pill start to be effective?', 'What are the advantages and disadvantages of the contraceptive pill?', 'When is the contraceptive pill contraindicated?', 'During the pill rest period should I use a condom?', 'What to do if you forget several birth control pills?' and 'What is the price of the contraceptive pill?'.

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Authors and contributors

 Andrea Rodrigo
Andrea Rodrigo
B.Sc., M.Sc.
Bachelor's Degree in Biotechnology from the Polytechnic University of Valencia. Master's Degree in Biotechnology of Human Assisted Reproduction from the University of Valencia along with the Valencian Infertility Institute (IVI). Postgraduate course in Medical Genetics. More information about Andrea Rodrigo
 Júlia Roig Navarro
Júlia Roig Navarro
Dr. Júlia Roig has a degree in Medicine and General Surgery from the University of Barcelona (UB). In addition, she is a specialist in Gynecology and Obstetrics at the Hospital Universitari Arnau de Vilanova and has a Master in Human Assisted Reproduction from the Complutense University of Madrid and did an internship at the Quirón Dexeus center in Barcelona. More information about Júlia Roig Navarro
Member number: 56030
 Sergio Rogel Cayetano
Sergio Rogel Cayetano
Bachelor's Degree in Medicine from the Miguel Hernández University of Elche. Specialist in Obstetrics & Gynecology via M. I. R. at Hospital General de Alicante. He become an expert in Reproductive Medicine by working at different clinics of Alicante and Murcia, in Spain, until he joined the medical team of IVF Spain back in 2011. More information about Sergio Rogel Cayetano
License: 03-0309100
 Silvia Azaña Gutiérrez
Silvia Azaña Gutiérrez
B.Sc., M.Sc.
Graduate in Health Biology from the University of Alcalá and specialized in Clinical Genetics from the same university. Master in Assisted Reproduction by the University of Valencia in collaboration with IVI clinics. More information about Silvia Azaña Gutiérrez
License: 3435-CV

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