Birth control pills (oral contraceptives) vs. Plan B (levonorgestrel)

  • Medical Editor: John P. Cunha, DO, FACOEP
    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.

Birth control pills vs. Plan B: What's the difference?

What are Birth Control Pills? What is Plan B?

Birth control pills (oral contraceptives) are used to prevent pregnancy. Birth control pills are hormonal preparations that typically contain combinations of the female hormones estrogen and progestin, or progestin alone. Combinations of estrogen and progestin inhibit the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland in the brain, which prevents pregnancy. LH and FSH have key roles in the development of the egg and preparation of the lining of the uterus so an embryo can implant itself. Progestin also makes uterine mucus that surrounds the egg more difficult for sperm to penetrate, which makes it more difficult for fertilization to take place. In some women, progestin inhibits ovulation (release of the egg).

Plan B (levonorgestrel) is emergency contraception (commonly called the morning after pill) that is used as backup contraception to prevent pregnancy when taken within 72 hours after unprotected sex or when birth control fails. Levonorgestrel is a progestin, which is a hormone used in many birth control pills. Although levonorgestrel and similar emergency contraception pills contain a higher dose of levonorgestrel than birth control pills, they work in a similar way to prevent pregnancy, mainly by stopping the release of an egg from the ovary. Additionally, levonorgestrel also may prevent fertilization of an egg (the uniting of the sperm with the egg) or prevent the attachment (implantation) of a fertilized egg to the uterus (womb). Emergency contraception pills do not work in women who are already pregnant and should not be taken during pregnancy.

What are the side effects of birth control pills and Plan B?

Oral contraceptives

The most common side effects of the birth control pills include nausea, headache, breast tenderness, weight gain, irregular bleeding, and mood changes. These side effects often subside after a few months' use. Scanty menstrual periods or breakthrough bleeding may occur but are often temporary, and neither side effect is serious. Women with a history of migraines may notice an increase in migraine frequency. On the other hand, women whose migraines are triggered by fluctuations in their own hormone levels may notice improvement in migraines with oral contraceptive use because of the more uniform hormone levels during oral contraceptive use.

Uncommonly, oral contraceptives may contribute to increased blood pressure, blood clots, heart attack, and stroke. Women who smoke, especially those over 35, and women with certain medical conditions, such as a history of blood clots or breast or endometrial cancer, may be advised against taking oral contraceptives, as these conditions can increase the adverse risks of oral contraceptives.

Plan B

Side effects include:

What are the dosages of birth control pills vs. Plan B?

Oral contraceptives

Many of the birth control pills come in easy-to-use dispensers in which the day of the week or a consecutive number (1, 2, 3, etc.) is written on the dispenser with a corresponding tablet for each day or number.

For example, some Ortho-Novum dispensers are labeled "Sunday" next to the first tablet. Thus, the first tablet is to be taken on the first Sunday after menstruation begins (the first Sunday following the first day of a woman's period). If her period begins on Sunday, the first tablet should be taken on that day.

For birth control pills that use consecutive numbers, the first tablet (#1) is taken on the first day of the menstrual period (the first day of bleeding). Tablet #2 is taken on the second day and so on.

Still other packages instruct women to begin on day five of the cycle. For such products, women count from day one of their menstrual cycle (day one is the first day of bleeding). On the fifth day, the first tablet is taken. Tablets then are taken daily.

Most birth control pills are packaged as 21-day or 28-day units. For 21-day packages, tablets are taken daily for 21 days. This is followed by a seven-day period during which no birth control pills are taken. Then the cycle repeats.

For the 28-day units, tablets containing medication are taken for 21 consecutive days, followed by a seven-day period during which placebo tablets (containing no medication) are taken.

Newer formulations with 24 days of hormone pills and only four days of placebo pills are now available, as are continuous or extended-cycle oral contraceptive regimens, in which only active hormone pills are taken. Extended-cycle preparations include seven-day intervals of placebo pills to be taken approximately every three months.

Women just starting to take birth control pills should use additional contraception for the first seven days of use because pregnancy may occur during this period.

If women forget to take tablets, pregnancy may result. If a single tablet is forgotten, it should be taken as soon as it is realized that it is forgotten. If more than one tablet is forgotten, the instructions that come with the packaging should be consulted, or a physician or pharmacist should be called.

Plan B

  • Emergency contraception pills should be taken as soon as possible and not more than 72 hours after unprotected sex or when birth control fails.
  • Single dose regimen: Take one 1.5 mg tablet as soon as possible within 72 hours of unprotected sex or when birth control fails.
  • Two-dose regimen: Take one 0.75 mg tablet as soon as possible within 72 hours of unprotected sex or when birth control fails, followed by a second 0.75 mg tablet 12 hours later.

What drugs interact with birth control pills and Plan B?

Oral contraceptives

Estrogens can inhibit the metabolism (elimination) of cyclosporine, resulting in increased cyclosporine blood levels. Such increased blood levels can result in kidney and/or liver damage. If this combination cannot be avoided, cyclosporine concentrations can be monitored, and the dose of cyclosporine can be adjusted to assure that its blood levels do not become elevated.

Estrogens appear to increase the risk of liver disease in patients receiving dantrolene (Dantrium) through an unknown mechanism. Women over 35 years of age and those with a history of liver disease are especially at risk.

Estrogens increase the liver's ability to manufacture clotting factors. Because of this, patients receiving warfarin (Coumadin) need to be monitored for loss of anticoagulant (blood thinning) effect if an estrogen is begun.

A number of medications, including some antibiotics and antiseizure medications, can decrease the blood levels of oral contraceptive hormones, but an actual decrease in the effectiveness of the oral contraceptive has not been convincingly proven. Nonetheless, because of this theoretical possibility, some physicians recommend backup contraceptive methods during antibiotic use. Examples of medications that increase the elimination of estrogens include

carbamazepine (Tegretol),
• phenobarbital,
phenytoin (Dilantin),
primidone (Mysoline),
• rifampin (Rifadin),
rifabutin (Mycobutin), and
ritonavir (Norvir).

Birth control pills with higher concentrations of estrogen or alternative forms of contraception may be necessary in women using those medications.

Plan B

Drugs or herbal products that increase the activity certain liver enzymes that breakdown drugs may reduce blood levels of levonorgestrel and the effectiveness of the morning after pill.

Subscribe to MedicineNet's General Health Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

Are birth control pills and Plan B safe to use while pregnant or breastfeeding?

Oral contraceptives

Use of birth control pills during lactation has been associated with decreased milk production, decreased infant weight gain, and decreased nitrogen and protein content of milk. The amount of estrogen consumed by an infant whose mother takes a standard dose of birth control pills is considered to be the same as from a lactating woman who is not taking birth control pills, and side effects have not been reported. Using a progestin-only product is most often recommended during lactation if birth control pills are to be used during this period. The American College of Obstetrics and Gynecology (ACOG) recommends delaying taking combined estrogen-progestin contraceptives until at least six weeks postpartum, while the World Health Organization (WHO) recommends delaying the initiation of combined contraceptives until six months.

Plan B

  • Emergency contraception pills will not work if you are already pregnant and should not be used during pregnancy.
  • Levonorgestrel is thought to enter human milk after oral administration and should be used cautiously in nursing mothers.

Summary

Birth control pills (oral contraceptives) and Plan B (levonorgestrel) are methods of birth control used to prevent pregnancy. Birth control pills are taken regularly to prevent pregnancy, while Plan B is emergency contraception (“the morning after pill”) used as backup contraception to prevent pregnancy when taken within 72 hours after unprotected sex or when birth control fails.

Treatment & Diagnosis

Medications & Supplements

Health Solutions From Our Sponsors

FDA Logo

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 5/20/2019
References
REFERENCES:

FDA Prescribing Information
CONTINUE SCROLLING FOR RELATED SLIDESHOW