What is oral levonorgestrel, and how does it work (mechanism of action)?
What is levonorgestrel-oral?
- Levonorgestrel (Plan B) is a type of 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. Progestins are hormones 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. Levonorgestrel will not prevent fertilization of an egg (the uniting of the sperm with the egg) and will not 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.
- The FDA approved levonorgestrel in July 1999.
What brand names are available for levonorgestrel-oral?
Plan B One-Step, Next Choice One Dose, My Way
Is levonorgestrel-oral available as a generic drug?
GENERIC AVAILABLE: Yes
Do I need a prescription for levonorgestrel-oral?
No. Most emergency contraception pills can be purchased over the counter or OTC (without a prescription). However, some age restrictions may apply.
What are the uses for oral levonorgestrel?
Emergency contraception pills are used to help prevent pregnancy after unprotected sex or when birth control methods fail. Emergency contraception is a backup method of preventing pregnancy and should not be used routinely.
What are the side effects of oral levonorgestrel?
Side effects include:
What is the dosage for oral levonorgestrel?
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.

SLIDESHOW
Sex-Drive Killers: The Causes of Low Libido See SlideshowWhich drugs or supplements interact with oral levonorgestrel?
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.
Is oral levonorgestrel safe to take if I'm pregnant or breastfeeding?
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.
What else should I know about oral levonorgestrel?
What preparations of levonorgestrel-oral are available?
Levonorgestrel is available as a blister pack containing two 0.75 mg tablets. Plan B One-Step, Next Choice One Dose, My Way are available as a blister pack containing one 1.5 mg tablet.
How should I store levonorgestrel-oral?
Levonorgestrel should be stored at room temperature between 15 C and 30 C (59 F and 86 F).
Summary
Levonorgestrel (Plan B One-Step, Next Choice One Dose, My Way) is a non-prescription (over-the-counter or OTC) drug used help prevent pregnancy when birth control methods fail or after unprotected sex. Side effects, drug interactions, storage, dosing, and pregnancy and breastfeeding safety should be reviewed prior to taking this medication.
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Related Disease Conditions
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Birth Control Options
Birth control is available in a variety of methods and types. The method of birth control varies from person to person, and their preferences to either become pregnant or not. Examples of barrier methods include barrier methods (sponge, spermicides, condoms), hormonal methods (pill, patch), surgical sterilization (tubal ligation, vasectomy), natural methods, and the morning-after pill. Side effects and risks of each birth control option should be reviewed before using any birth control method.
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Pregnancy Planning (Tips)
Pregnancy planning is an important step in preparation for starting or expanding a family. Planning for a pregnancy includes taking prenatal vitamins, eating healthy for you and your baby, disease prevention (for both parents and baby) to prevent birth defects and infections, avoiding certain medications that may be harmful to your baby, how much weight gain is healthy exercise safety and pregnancy, travel during pregnancy.
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DVT and Birth Control Pills (Oral Contraceptives)
Deep vein thrombosis (DVT) is a blood clot that has traveled deep into the veins of the arm, pelvis, or lower extremities. Oral contraceptives or birth control pills can slightly increase a woman's risk for developing blood clots, including DVT. DVT symptoms and signs in the leg include leg or calf pain, redness, swelling, warmth, or leg cramps, and skin discoloration. If a blood clot in the leg is not treated, it can travel to the lungs, which can cause a pulmonary embolism (blood clot in the lung) or post-thrombotic syndrome, both of which can be fatal if not treated immediately. Increased risk factors for DVT and birth control pills include over 40 years of age, family history, smoking, and obesity. Other medical problems that increase the risks of blood clots, for example, lung or heart disease, or inflammatory bowel disease or IBD (Crohn's disease and ulcerative colitis (UC). Other options for preventing pregnancy include IUDs, birth control shots, condoms, diaphragms, and progestin-only oral contraceptives.
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How Effective Is Plan B?
Plan B, or the morning after pill, is almost 95% effective at preventing pregnancy if taken within 24 hours of unprotected sex, and 87% effective if taken within 72 hours.
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Sexual Health
Sexual health information including birth control, impotence, herpes, sexually transmitted diseases, staying healthy, women's sexual health concerns, and men's sexual health concerns. Learn about the most common sexual conditions affecting men and women.
Treatment & Diagnosis
- Natural Birth Control
- IUD (Intrauterine Device for Birth Control)
- Birth Control: Surgical Sterilization
- What Are the Chances of Plan B Failing?
- Hormonal Methods of Birth Control
- Barrier Methods of Birth Control Side Effects, Advantages, and Disadvantages
- Contraceptive Measures after Unprotected Sex
- Childbirth Class Options
Medications & Supplements
Prevention & Wellness

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.