Oral Contraceptives

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Oral Contraceptives



Oral contraceptives are medicines taken by mouth to help prevent pregnancy. They are also known as the Pill, OCs, or birth control pills.


Oral contraceptives, also known as birth control pills, contain artificially made forms of two hormones produced naturally in the body. These hormones, estrogen and progestin, regulate a woman's menstrual cycle. When taken in the proper amounts, following a specific schedule, oral contraceptives are very effective in preventing pregnancy. Studies show that less than one of every one hundred women who use oral contraceptives correctly becomes pregnant during the first year of use.
These pills have several effects that help prevent pregnancy. For pregnancy to occur, an egg must become mature inside a woman's ovary, be released, and travel to the fallopian tube. A male sperm must also reach the fallopian tube, where it fertilizes the egg. Then the fertilized egg must travel to the woman's uterus (womb), where it lodges in the uterus lining and develops into a fetus. The main way that oral contraceptives prevent pregnancy is by keeping an egg from ripening fully. Eggs that do not ripen fully cannot be fertilized. In addition, birth control pills thicken mucus in the woman's body through which the sperm has to swim. This makes it more difficult for the sperm to reach the egg. Oral contraceptives also change the uterine lining so that a fertilized egg cannot lodge there to develop.
Birth control pills may cause good or bad side effects. For example, a woman's menstrual periods are regular and usually lighter when she is taking oral contraceptives, and the pills may reduce the risk of ovarian cysts, breast lumps, pelvic inflammatory disease, and other medical problems. However, taking birth control pills increases the risk of heart attack, stroke, and blood clots in certain women. Serious side effects such as these are more likely in women over 35 years of age who smoke cigarettes and in those with specific health problems such as high blood pressure, diabetes, or a history of breast or uterine cancer. A woman who wants to use oral contraceptives should ask her physician for the latest information on the risks and benefits of all types of birth control and should consider her age, health, and medical history when deciding what to use.


No form of birth control (except not having sex) is 100% effective. However, oral contraceptives can be highly effective when used properly. Discuss the options with a health care professional.
Oral contraceptives do not protect against AIDS or other sexually transmitted diseases. For protection against such diseases, use a latex condom.
Oral contraceptives are not effective immediately after a woman begins taking them. Physicians recommend using other forms of birth control for the first 1-3 weeks. Follow the instructions of the physician who prescribed the medicine.
Smoking cigarettes while taking oral contraceptives greatly increases the risk of serious side effects. Women who take oral contraceptives should not smoke cigarettes.
Seeing a physician regularly while taking this medicine is very important. The physician will note unwanted side effects. Follow his or her advice on how often you should be seen.
Anyone taking oral contraceptives should be sure to tell the health care professional in charge before having any surgical or dental procedures, laboratory tests, or emergency treatment.
This medicine may increase sensitivity to sunlight. Women using oral contraceptives should avoid too much sun exposure and should not use tanning beds, tanning booths, or sunlamps until they know how the medicine affects them. Some women taking oral contraceptives may get brown splotches on exposed areas of their skin. These usually go away over time after the women stop taking birth control pills.
Oral contraceptives may cause the gums to become tender and swollen or to bleed. Careful brushing and flossing, gum massage, and regular cleaning may help prevent this problem. Check with a physician or dentist if gum problems develop.
Women who have certain medical conditions or who are taking certain other medicines may have problems if they take oral contraceptives. Before taking these drugs, be sure to let the physician know about any of these conditions:
ALLERGIES. Anyone who has had unusual reactions to estrogens or progestins in the past should let her physician know before taking oral contraceptives. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.
PREGNANCY. Women who become pregnant or think they may have become pregnant while taking birth control pills should stop taking them immediately and check with their physicians. Women who want to start taking oral contraceptives again after pregnancy should not refill their old prescriptions without checking with their physicians. The physician may need to change the prescription.
BREASTFEEDING. Women who are breastfeeding should check with their physicians before using oral contraceptives. The hormones in the pills may reduce the amount of breast milk and may cause other problems in breastfeeding. They may also cause jaundice and enlarged breasts in nursing babies whose mothers take the medicine.
OTHER MEDICAL CONDITIONS. Oral contraceptives may improve or worsen some medical conditions. The possibility that they may make a condition worse does not necessarily mean they cannot be used. In some cases, women may need only to be tested or followed more closely for medical problems while using oral contraceptives. Before using oral contraceptives, women with any of these medical problems should make sure their physicians are aware of their conditions:
  • Female conditions such as menstrual problems, endometriosis, or fibroid tumors of the uterus. Birth control pills usually make these problems better, but may sometimes make them worse or more difficult to diagnose.
  • Heart or circulation problems; recent or past blood clots or stroke. Women who already have these problems may be at greater risk of developing blood clots or circulation problems if they use oral contraceptives. However, healthy women who do not smoke may lower their risk of circulation problems and heart disease by taking the pills.
  • Breast cysts, lumps, or other noncancerous breast problems. Oral contraceptives generally protect against these conditions, but physicians may recommend more frequent breast exams for women taking the pills.
  • Breast cancer or other cancer (now or in the past, or family history). Oral contraceptives may make some existing cancers worse. Women with a family history of breast cancer may need more frequent screening for the disease if they decide to take birth control pills.
  • Migraine headaches. This condition may improve or may get worse with the use of birth control pills.
  • Diabetes. Blood sugar levels may increase slightly when oral contraceptives are used. Usually this increase is not enough to affect the amount of diabetes medicine needed. However, blood sugar will need to be monitored closely while taking oral contraceptives.
  • Depression. This condition may worsen in women who already have it or may (rarely) occur again in women who were depressed in the past.
  • Gallbladder disease, gallstones, high blood cholesterol, or chorea gravidarum (a nervous disorder). Oral contraceptives may make these conditions worse.
  • Epilepsy, high blood pressure, heart or circulation problems. By increasing fluid build-up, oral contraceptives may make these conditions worse.


Oral contraceptives (birth control pills) come in a wide range of estrogen-progestin combinations. The pills in use today contain much lower doses of estrogen than those available in the past, and this change has reduced the likelihood of serious side effects. Some pills contain only progestin. These are prescribed mainly for women who need to avoid estrogens and may not be as effective in preventing pregnancy as the estrogen-progestin combinations.
These medicines come in tablet form, in containers designed to help women keep track of which tablet to take each day. The tablets are different colors, indicating amounts of hormones they contain. Some may contain no hormones at all. These are included simply to help women stay in the habit of taking a pill every day, as the hormone combination needs to be taken only on certain days of the menstrual cycle. Keeping the tablets in their original container and taking them exactly on schedule is very important. They will not be as effective if they are taken in the wrong order or if doses are missed.
Oral contraceptives are available only with a physician's prescription. Some commonly used brands are Demulen, Desogen, Loestrin, Lo/Ovral, Nordette, Ortho-Novum, Ortho-Tri-Cyclen, Estrostep, Orthocept, Alesse, Levlite and Ovcon.
The dose schedule depends on the type of oral contraceptive. The two basic schedules are a 21-day schedule and a 28-day schedule. On the 21-day schedule, take one tablet a day for 21 days, then skip 7 days and repeat the cycle. On the 28-day schedule, take one tablet a day for 28 days; then repeat the cycle. Be sure to carefully follow the instructions provided with the medicine. For additional information or explanations, check with the physician who prescribed the medicine or the pharmacist who filled the prescription.
Taking doses more than 24 hours apart may increase the chance of side effects or pregnancy. Try to take the medicine at the same time every day. Take care not to run out of pills. If possible, keep an extra month's supply on hand and replace it every month with the most recently filled prescription.
Try not to miss a dose, as this increases the risk of pregnancy. If a dose is missed, follow the package directions or check with the physician who prescribed the medicine for instructions. It may be necessary to use another form of birth control for some time after missing a dose.
Taking this medicine with food or at bedtime will help prevent nausea, a side effect that sometimes occurs during the first few weeks. This side effect usually goes away as the body adjusts to the medicine.
Taking oral contraceptives may have several benefits outside of their ability to prevent pregnancy. Research indicates that with 10 to 12 years of oral contraceptive use, a woman's risk of ovarian cancer is reduced by up to 80%. There may also be an approximate 50% decrease in the rate of endometrial cancers in women. One other well-known, noncontraceptive benefit of oral contraceptives is an improvement in acne. The combination oral contraceptive ethinyl estradiol/norgestimate has been approved by the Food and Drug Administration for the treatment of acne. Another positive effect of oral contraceptive use is improvement in abnormal uterine bleeding. Older women may also benefit from using oral contraceptives, because the pills can increase bone mass as women enter their menopausal years, when osteoporosis is a growing concern.
Oral contraceptives may also be used on an emergency basis as a means of preventing pregnancy in women who have had unprotected intercourse. Two products specifically designed for this purpose are Preven and Plan B. In 2001, the American College of Obstetricians and Gynecologists (ACOG) recommended that emergency oral contraceptives be available as an over-the-counter medicine. The Food and Drug Administration, however, has not yet approved any measures that would allow this to happen.


Taking oral contraceptives with certain other drugs may affect the way the drugs work or may increase the chance of side effects.

Side effects

Serious side effects are rare in healthy women who do not smoke cigarettes. In women with certain health problems, however, oral contraceptives may cause problems such as liver cancer, noncancerous liver tumors, blood clots, or stroke. Health care professionals can help women weigh the benefits of being protected against unwanted pregnancy against the risks of possible health problems.
The most common minor side effects are nausea; vomiting; abdominal cramping or bloating; breast pain, tenderness or swelling; swollen ankles or feet; tiredness; and acne. These problems usually go away as the body adjusts to the drug and do not need medical attention unless they continue or they interfere with normal activities.
Other side effects should be brought to the attention of the physician who prescribed the medicine. Check with the physician as soon as possible if any of the following side effects occur:
  • menstrual changes, such as lighter periods or missed periods, longer periods, or bleeding or spotting between periods
  • headaches
  • vaginal infection, itching, or irritation
  • increased blood pressure
Women who have any of the following symptoms should get emergency help right away. These symptoms may be signs of blood clots:
  • sudden changes in vision, speech, breathing, or coordination
  • severe or sudden headache
  • coughing up blood
  • sudden, severe, or continuing pain in the abdomen or stomach
  • pain in the chest, groin, or leg (especially in the calf)
  • weakness, numbness, or pain in an arm or leg
Oral contraceptives may continue to affect the menstrual cycle for some time after a woman stops taking them. Women who miss periods for several months after stopping this medicine should check with their physicians.
Other rare side effects may occur. Anyone who has unusual symptoms while taking oral contraceptives should get in touch with her physician.


Oral contraceptives may interact with a number of other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effects may be greater. Anyone who takes oral contraceptives should let the physician know all other medicines she is taking and should ask whether the possible interactions can interfere with drug therapy.
These drugs may make oral contraceptives less effective in preventing pregnancy. Anyone who takes these drugs should use an additional birth control method for the entire cycle in which the medicine is used:
  • ampicillin
  • penicillin V
  • rifampin (Rifadin)
  • tetracyclines
  • griseofulvin (Gris-PEG, Fulvicin)
  • corticosteroids
  • barbiturates
  • carbamazepine (Tegretol)
  • phenytoin (Dilantin)
  • primidone (Mysoline)
  • ritonavir (Norvir)
In addition, taking these medicines with oral contraceptives may increase the risk of side effects or interfere with the medicine's effects:
  • theophylline-effects of this medicine may increase, along with the chance of unwanted side effects
  • cyclosporine-effects of this medicine may increase, along with the chance of unwanted side effects
  • troleandomycin (TAO)-chance of liver problems may increase. Effectiveness of oral contraceptive may also decrease, raising the risk of pregnancy
The list above does not include every drug that may interact with oral contraceptives. Be sure to check with a physician or pharmacist before combining oral contraceptives with any other prescription or nonprescription (over-the-counter) medicine.
As with any medication, the benefits and risks should be discussed with a physician.



Beers, Mark H., and Robert Berkow, editors. The Merck Manual of Diagnosis and Therapy. 17th ed. Whitehouse Station, NJ: Merck and Company, Inc., 1999.


"Current Perspectives on OC Formulations." Family Practice News January 15, 2001: 2.
"Physician Group Supports Safety, Availability of Over-the-Counter Emergency Option." Medical Letter on the CDC and FDA March 18, 2001.


Medline Plus Health Information, U.S. National Library of Medicine. http://www.nlm.nih.gov/medlineplus.

Key terms

Cyst — An abnormal sac or enclosed cavity in the body, filled with liquid or partially solid material.
Endometriosis — A condition in which tissue like that normally found in the lining of the uterus is present outside the uterus. The condition often causes pain and bleeding.
Fallopian tube — One of a pair of slender tubes that extend from each ovary to the uterus. Eggs pass through the fallopian tubes to reach the uterus.
Fetus — A developing baby inside the womb.
Fibroid tumor — A noncancerous tumor formed of fibrous tissue.
Hormone — A substance that is produced in one part of the body, then travels through the bloodstream to another part of the body where it has its effect.
Jaundice — Yellowing of the eyes and skin due to the build up of a bile pigment (bilirubin) in the blood.
Migraine — A throbbing headache that usually affects only one side of the head. Nausea, vomiting, increased sensitivity to light, and other symptoms often accompany migraine.
Mucus — Thick fluid produced by the moist membranes that line many body cavities and structures.
Ovary — A reproductive organ in females that produces eggs and hormones.
Pelvic inflammatory disease — Inflammation of the female reproductive tract, caused by any of several microorganisms. Symptoms include severe abdominal pain, high fever, and vaginal discharge. Severe cases can result in sterility. Also called PID.
Uterus — A hollow organ in a female in which a fetus develops until birth.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
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Little evidence exists that compares different types of oral contraceptives. Many of the physical attributes of the singers were either not controlled or not factored into the analysis including Fach, vocal ability, age, and weight.
University of Aberdeen (Scotland) led the analysis, which looked at data from more than 35,000 women (from an original cohort of 46,000) and identified 4,661 ever-users of combined oral contraceptive who had at least one cancer during more than 884,000 woman-years of observation, and 2,341 women who had never used combined OCs but who had at least one cancer during more than 388,000 years of observation.
In women with other stroke risk factors, the risk is higher and, in most cases, oral contraceptive use is discouraged.
For a patient beginning oral contraceptives, it's not necessary to perform a pelvic exam or obtain a Pap smear before initiating the COC, but it is important to obtain a thorough medical history and an accurate blood pressure measurement at the outset, she noted.
know from evidence and experience that oral contraceptives are safe enough for OTC access.
Around 100 million women use one of the 40 oral contraceptives or have used one of the 21 brands of emergency contraceptives on the market in the United States.
About nine per cent of women of reproductive age worldwide use oral contraceptives, rising to 18 per cent of women in developed countries and 28 per cent of women in the UK.
These findings led the World Health Organization and the American Congress of Obstetricians and Gynecologists to regard migraine with aura as an "absolute contraindication" against the use of combined oral contraceptives, Dr.
This study was carried out to compare the effects of injectable hormonal contraceptives and oral contraceptives on blood pressure and electrolytes among Pakistani women within reproductive age.