Birth control pills come in a variety of formulations. The main division is between

combined oral contraceptive pill The combined oral contraceptive pill (COCP), often referred to as the birth control pill or colloquially as "the pill", is a type of birth control that is designed to be taken orally by women. The pill contains two important hormones: proges ...

s, containing both

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...

s and synthetic progestogens ( progestins), and

progestogen only pill Progestogen-only pills or progestin-only pills (POP) are contraceptive pills that contain only synthetic progestogens ( progestins) and do not contain estrogen. They are colloquially known as mini pills. Although such pills are sometimes called ...

s. Combined oral contraceptive pills also come in varying types, including varying doses of estrogen, and whether the dose of estrogen or progestogen changes from week to week.

Mechanism of action

Combination pills usually work by preventing the

ovaries The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. T ...

from releasing eggs (

ovulation Ovulation is the release of eggs from the ovaries. In women, this event occurs when the ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilize ...

). They also thicken the cervical mucus, which keeps sperm from penetrating into the uterus and joining with an egg. The hormones in combination and progestogen-only pills also thin the lining of the

uterus The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The ...

. This could prevent

pregnancy Pregnancy is the time during which one or more offspring develops (gestation, gestates) inside a woman, woman's uterus (womb). A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occur ...

by interfering with implantation of a blastocyst. Main action in typical use is prevention of ovulation.

Combined oral contraceptive pills

All contain an estrogen,

ethinylestradiol Ethinylestradiol (EE) is an estrogen medication which is used widely in birth control pills in combination with progestins. In the past, EE was widely used for various indications such as the treatment of menopausal symptoms, gynecological disord ...

or mestranol, in varying amounts, and one of a number of different progestogens. (Regarding the estrogen, the inactive 3-methyl ether of ethinylestradiol, which must be metabolized by the liver into the active ethinylestradiol; 50 μg of mestranol is equivalent to only 35 μg of ethinylestradiol and should not be used when high-dose 0 μg ethinylestradiolestrogen pills are needed; mestranol was the estrogen used in the first oral contraceptive, Enovid). They are usually taken for 21 days with then a seven-day gap during which a withdrawal bleed (often, but incorrectly, referred to as a

menstrual period The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that make pregnancy possible. The ovarian cycle controls the production and release of eggs ...

) occurs. These differ in the amount of estrogen given, and whether they are monophasic (the same dose of estrogen and progestogen during each of the 21 days) or multiphasic (varying doses). The introduction of extended-cycle monophasic pills (i.e. Seasonale) has shown that the withdrawal bleeding intervals can be decreased.

Monophasic

These are typically given as 21 tablets of estrogen and progestogen, followed by seven tablets of placebo or an

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

supplement, although some newer formulations contain more active tablets and fewer placebos. Everyday regimens (Microgynon 30 ED, Femodene ED, Logynon ED), which include seven inactive placebo pills, are rarely used in UK practice. Different formulations contain different amounts of estrogen and progestogen: * 15 μg ethinylestradiol ** 60 μg

gestodene Gestodene, sold under the brand names Femodene and Minulet among others, is a progestin medication which is used in birth control pills for women. It is also used in menopausal hormone therapy. The medication is available almost exclusively in ...

: 24 days + 4 days placebo (Spain: Melodene-15; Israel: Minesse) * 20 μg ethinylestradiol ** 1000 μg

norethisterone acetate Norethisterone acetate (NETA), also known as norethindrone acetate and sold under the brand name Primolut-Nor among others, is a progestin medication which is used in birth control pills, menopausal hormone therapy, and for the treatment of gyn ...

(UK: Loestrin 20, Galen; US: Loestrin 1/20, Duramed; Microgestin 1/20, Watson Pharmaceuticals; Junel 1/20,

Barr Barr may refer to: Places * Barr (placename element), element of place names meaning 'wooded hill', 'natural barrier' * Barr, Ayrshire, a village in Scotland * Barr Building (Washington, DC), listed on the US National Register of Historic Places ...

) ** 1000 μg norethisterone acetate: 24 days + 4 days ferrous fumarate only (US: Loestrin 24 Fe,

Warner Chilcott Warner Chilcott (formerly Galen) was a company in the pharmaceutical industry based in Rockaway, New Jersey. It was primarily focused on women’s healthcare and dermatology. On October 1, 2013, the company was acquired by Actavis (now Allergan). ...

) ** 90 μg levonorgestrel: continuous: 365 days/year, no placebo (US: Amethyst, Watson) ** 100 μg levonorgestrel: extended cycle: 84 days + 7 days 10 μg ethinylestradiol only (US: LoSeasonique, Teva; CamreseLo, Teva) ** 100 μg levonorgestrel (US: Alesse, Wyeth; Aviane, Barr; Lessina, Barr; Lutera, Watson; Sronyx, Watson) ** 150 μg

desogestrel Desogestrel is a progestin medication which is used in birth control pills for women. It is also used in the treatment of menopausal symptoms in women. The medication is available and used alone or in combination with an estrogen. It is taken b ...

(UK: Mercilon,

Organon The ''Organon'' ( grc, Ὄργανον, meaning "instrument, tool, organ") is the standard collection of Aristotle's six works on logical analysis and dialectic. The name ''Organon'' was given by Aristotle's followers, the Peripatetics. The six ...

; HU: Novynette, Richter Gedeon) ** 75 μg

(UK: Femodette, Bayer; RU: Logest, Bayer; Brazil: Femiane, Bayer) ** 3000 μg

drospirenone Drospirenone is a progestin and antiandrogen medication which is used in birth control pills to prevent pregnancy and in menopausal hormone therapy, among other uses. It is available both alone under the brand name Slynd and in combination wi ...

: 24 days + 4 days placebo (US, EU, RU: Yaz; Bayer Schering Pharma AG. Cleonita); 21 days + 7 days placebo (US, EU: , Bayer); 24 days + 4 days placebo and levomefolate calcium (US: Beyaz; Bayer) * 30 μg ethinylestradiol ** 1500 μg norethisterone acetate (UK: Loestrin 30, Galen; US: Loestrin 1.5/30, Duramed; Microgestin 1.5/30, Watson; Junel 1.5/30, Barr) ** 300 μg norgestrel (US: Lo/Ovral, Wyeth; Low-Ogestrel, Watson; Cryselle, Barr) ** 150 μg levonorgestrel (UK: Ovranette, Wyeth; Microgynon 30, Microgynon 30 ED, Bayer; US: Nordette, Duramed, Levora, Watson, Portia, Barr) ** 150 μg levonorgestrel: 21 day cycle + 7 days no pills (Canada: Min-Ovral 21; EU: Ovoplex 150/30; Sweden: , ) ** 150 μg levonorgestrel: 21 day cycle + 7 days placebo (Canada: Min-Ovral 28; Sweden: ; RU: Rigevidon 21+7, Richter Gedeon) ** 150 μg levonorgestrel: extended cycle: 84 days + 7 days placebo (US: Seasonale, Duramed; Quasense, Watson; Jolessa, Barr, Introvale) ** 150 μg levonorgestrel: extended cycle: 84 days + 7 days 10 μg ethinylestradiol only (US: Seasonique, Duramed; Camrese, Teva; Amethia, Watson) ** 75 μg gestodene (UK: Femodene, Femodene ED, Bayer; Minulet, Wyeth; RU: Femoden,

Jenapharm Jenapharm is a pharmaceutical company from Jena, Germany. Founded in 1950 in East Germany, the company focused from the beginning on the production and development of steroids. Due to the economic circumstances of the Eastern Bloc, the company ini ...

) ** 150 μg desogestrel (AU, EU, RU, UK: Marvelon, BR: Microdiol, US: Desogen, MSD; US: Ortho-Cept, Ortho-McNeil; RU: Regulon, Richter Gedeon) ** 3000 μg

(AU, EU, US: Yasmin, FR: Jasmine, RU: Yarina, Bayer Schering Pharma AG); with levomefolate calcium (US: Safyral, Bayer Schering Pharma AG) ** 2000 μg

chlormadinone acetate Chlormadinone acetate (CMA), sold under the brand names Belara, Gynorelle, Lutéran, and Prostal among others, is a progestin and antiandrogen medication which is used in birth control pills to prevent pregnancy, as a component of menopausal hor ...

(EU: Belara,

Benelux The Benelux Union ( nl, Benelux Unie; french: Union Benelux; lb, Benelux-Unioun), also known as simply Benelux, is a politico- economic union and formal international intergovernmental cooperation of three neighboring states in western Europe: ...

: Bellina; Gedeon Richter) ** 2000 μg

dienogest Dienogest, sold under the brand name Visanne among others, is a progestin medication which is used in birth control pills and in the treatment of endometriosis. It is also used in menopausal hormone therapy and to treat heavy periods. Dienogest ...

(AU, EU: Valette, RU: Jeanine, Bayer Schering Pharma AG; RU: Siluet, Gedeon Richter) * 35 μg ethinylestradiol ** 400 μg norethisterone: chewable,

spearmint Spearmint, also known as garden mint, common mint, lamb mint and mackerel mint, is a species of mint, ''Mentha spicata'' (, native to Europe and southern temperate Asia, extending from Ireland in the west to southern China in the east. It is nat ...

flavor (US: Femcon Fe, Warner Chilcott) ** 400 μg norethisterone (US: Ovcon 35, Warner Chilcott; Balziva, Barr) ** 500 μg norethisterone (UK: Ovysmen, Janssen-Cilag; Brevinor,

Pfizer Pfizer Inc. ( ) is an American multinational pharmaceutical and biotechnology corporation headquartered on 42nd Street in Manhattan, New York City. The company was established in 1849 in New York by two German entrepreneurs, Charles Pfizer ...

; US: Modicon, Ortho-McNeil; Brevicon, Watson; Nortrel 0.5/35, Barr) ** 1000 μg norethisterone (AU, CAN: Synphasic, Pfizer; UK: Norimin, Pfizer; US: Ortho-Novum 1/35, Ortho-McNeil; Norinyl 1/35, Watson; Necon, Watson; Nortrel 1/35, Barr) ** 1000 μg

etynodiol diacetate Etynodiol diacetate, or ethynodiol diacetate, sold under the brand names Demulen and Femulen among others, is a progestin medication which is used in birth control pills. The medication is available only in combination with an estrogen. It is t ...

(US: Demulen 1/35, Pfizer; Zovia 1/35, Watson; Kelnor, Barr) ** 250 μg norgestimate (UK: Cilest, Janssen-Cilag; US: Ortho Cyclen, Ortho-McNeil; MonoNessa, Watson; Sprintec, Barr; Sweden: ) ** 2000 μg

cyproterone acetate Cyproterone acetate (CPA), sold alone under the brand name Androcur or with ethinylestradiol under the brand names Diane or Diane-35 among others, is an antiandrogen and progestin medication used in the treatment of androgen-dependent condition ...

: only approved for severe

acne Acne, also known as ''acne vulgaris'', is a long-term skin condition that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and ...

or severe

hirsutism Hirsutism is excessive body hair on parts of the body where hair is normally absent or minimal. The word is from early 17th century: from Latin ''hirsutus'' meaning "hairy". It usually refers to a "male" pattern of hair growth in a female that ...

in the UK (AU, RU: Diane-35, UK: Dianette, Bayer) * 50 μg mestranol (equivalent to 35 μg ethinylestradiol) ** 1000 μg norethisterone (UK: Norinyl-1, Pfizer; US: Ortho-Novum 1/50; Ortho-McNeil; Norinyl 1/50, Watson; Necon 1/50, Watson) * 50 μg ethinylestradiol ** 1000 μg norethisterone (US: Ovcon 50, Warner Chilcott) ** 1000 μg etynodiol diacetate (US: Demulen 1/50, Pfizer; Zovia 1/50, Watson) ** 500 μg norgestrel (US: Ogestrel, Watson) ** 250 μg levonorgestrel (US: Nordiol, Wyeth) * 1.5 mg estradiol (as hemihydrate) ** 2.5 mg

nomegestrol acetate Nomegestrol acetate (NOMAC), sold under the brand names Lutenyl and Zoely among others, is a progestin medication which is used in birth control pills, menopausal hormone therapy, and for the treatment of gynecological disorders.http://www.ema. ...

: 24-day cycle + 4 placebo pills (AU, EU, RU: Zoely, MSD) *15 mg estetrol monohydrate (equivalent to 14.2 mg estetrol) **3 mg drospirenone: 24-day cycle + 4 inactive pills (US, CAN: Nexstellis, Mayne, EU: Drovelis, Gedeon Richter Plc., EU: Lydisilka, Estetra SRL)

Multiphasic

* 25 μg ethinylestradiol: triphasic ** ethinylestradiol/norgestimate combination with 7 tablets 25 μg/180 μg, 7 tablets 25 μg/215 μg, 7 tablets 25 μg/250 μg followed by 7 placebos (Ortho Tri-Cyclen Lo from Ortho-McNeil, Tri-Lo Sprintec back from Teva, Tri-Lo Marzia from Lupin, and norgestimate/ethinylestradiol from Mylan) ** ethinylestradiol/desogestrel combination with 7 tablets 25 μg/100 μg, 7 tablets 25 μg/125 μg, 7 tablets 25 μg/150 μg, followed by 7 tablets of ferric oxide (US: Cyclessa, Organon; Velivet, Barr) * 20/30/35 μg ethinylestradiol: estrophasic ** ethinylestradiol/norethisterone acetate combination with 5 tablets 20 μg/1000 μg, 7 tablets 30 μg/1000 μg, 9 tablets 35 μg/1000 μg, followed by 7 tablets of ferrous fumarate 75 mg (US: Estrostep Fe, Warner Chilcott) * 35/30/30 μg ethinylestradiol: triphasic ** ethinylestradiol/desogestrel combination with 7 tablets 35 μg/50 μg, 7 tablets 30 μg/100 μg, 7 tablets 30 μg/150 μg (RU: Tri-Merci, Organon) * 30/40/30 μg ethinylestradiol: triphasic ** ethinylestradiol/levonorgestrel combination with 6 tablets 30 μg/50 μg, 5 tablets 40 μg/75 μg, 10 tablets 30 μg/125 μg (UK: Trinordiol, Wyeth; Logynon, Logynon ED, Bayer; US: Triphasil, Wyeth; Trivora, Watson; , Barr) ** ethinylestradiol/gestodene combination with 6 tablets 30 μg/50 μg, 5 tablets 40 μg/70 μg, 10 tablets 30 μg/100 μg (UK: Triadene, Bayer; Tri-Minulet, Wyeth) * 35 μg ethinylestradiol: triphasic ** ethinylestradiol/norethisterone combination with 7 tablets 35 μg/500 μg, 9 tablets 35 μg/1000 μg, 5 tablets 35 μg/500 μg (UK: Synphase, Pfizer; US: Tri-Norinyl, Watson; Leena, Watson) ** ethinylestradiol/norethisterone combination with 7 tablets 35 μg/500 μg, 7 tablets 35 μg/750 μg, 7 tablets 35 μg/1000 μg (UK: TriNovum, Janssen-Cilag; US: Ortho-Novum 7/7/7, Ortho-McNeil; Necon 7/7/7, Watson; Nortrel 7/7/7, Barr) ** ethinylestradiol/norgestimate combination with 7 tablets 35 μg/180 μg, 7 tablets 35 μg/215 μg, 7 tablets 35 μg/250 μg followed by 7 placebos (Ortho Tri-Cyclen, Ortho-McNeil; TriNessa, Watson; Tri-Sprintec, Barr) * 35 μg ethinylestradiol: biphasic ** ethinylestradiol/norethisterone combination with 10 tablets 35 μg/500 μg, 11 tablets 35 μg/1000 μg, followed by 7 placebos (US: Ortho-Novum 10/11, Ortho-McNeil; Necon 10/11, Watson) ** ethinylestradiol/norethisterone combination with 7 tablets 35 μg/500 μg, 14 tablets 35 μg/1000 μg (UK: BiNovum, Janssen-Cilag) * 3/2/1 mg

estradiol valerate Estradiol valerate (EV), sold for use by mouth under the brand name Progynova and Primiwal E4 and for use by injection under the brand names Delestrogen and Progynon Depot among others, is an estrogen medication. It is used in hormone therapy fo ...

: estrophasic ** estradiol valerate/

combination with 2 tablets 3 mg/0 mg, followed by 5 tablets 2 mg/2 mg, 17 tablets 2 mg/3 mg, 2 tablets 1 mg/0 mg, and 2 placebos. (AU, EU, RU: Qlaira, US: Natazia, Bayer)

Progestogen-only pills

Progestogen-only pills (POPs) use a progestogen alone with doses taken continuously and no or a short gap between packs taken. People who use them may experience irregular light bleeds, and whilst irregular in the first few months of taking, usually settles to a regular pattern in time. The following progestogens are used: * 350 μg norethisterone (norethindrone) (UK: Micronor, Janssen-Cilag; Noriday, Pfizer; US: Micronor, Ortho-McNeil; Nor-QD, Watson; Nora-BE, Watson; Jolivette, Watson; Camila, Barr; Errin, Barr; Heather, Glenmark; RU: Primolut-Nor, Bayer; Norkolut, Richter Gedeon) * 4 mg

(Slynd) * 75 μg

(UK: Cerazette, Loestrin; RU: Cerazette, Organon; Lactinette, Richter Gedeon; SE: Gestrina) * 30 μg levonorgestrel (UK: Norgeston, Bayer; AUS, RU: Microlut, Bayer) * 500 μg

(UK: Femulen, Pfizer) * 500 μg lynestrenol (RU: Exluton, Organon)

Contraindications

Generally oral contraceptives should not be used in people who currently have the following conditions: * Thrombophlebitis or thromboembolic disorders * A history of deep vein thrombophlebitis or thromboembolic disorders * Cerebrovascular or coronary artery disease (current or history) * Valvular heart disease with thrombogenic complications * Severe hypertension * Diabetes with vascular involvement * Headaches with focal neurological symptoms * Major surgery with prolonged immobilization * Known or suspected carcinoma of the breast or personal history of breast cancer * Carcinoma of the endometrium or other known or suspected estrogen-dependent neoplasia * Undiagnosed abnormal genital bleeding * Cholestatic jaundice of pregnancy or jaundice with prior pill use * Hepatic adenomas or carcinomas, or active liver disease * Known or suspected pregnancy * Hypersensitivity to any component of the product More comprehensive guidelines that include analysis of risks and benefits can be found in the World Health Organization Medical Eligibility for Contraceptive Use Guidelines which are reflected in the CDC Medical Eligibility for Contraceptive Use Guidelines.

References

{{Progesterone receptor modulators Combined oral contraceptives