Plan B One-Step

Generic name: levonorgestrel emergency contraceptive [ LEE-voe-nor-jes-trel ]
Brand name: Plan B One-Step
Drug classes: Contraceptives, Progestins

Medically reviewed by Philip Thornton, DipPharm. Last updated on Oct 31, 2021.

What is Plan B One-Step?

Plan B is a female hormone that can cause changes in your cervix, making it harder for sperm to reach the uterus and harder for a fertilized egg to attach to the uterus.

Plan B One-Step is used to prevent pregnancy after unprotected sex or failure of other forms of birth control (such as condom breakage, or missing 2 or more birth control pills).

Plan B One-Step is a backup method of preventing pregnancy and should not be used as regular birth control.

Warnings

Do not use Plan B One-Step if you are already pregnant. Levonorgestrel will not terminate a pregnancy that has already begun (the fertilized egg has attached to the uterus).

Plan B One-Step is not intended for use as a routine form of birth control and should not be used in this manner. Talk with your doctor about the many forms of birth control available.

Any person, regardless of age, can purchase Plan B One-Step right off the shelf without a prescription, ID or age requirement at all major retailers in the U.S.

Ask a doctor or pharmacist before taking this medicine if you regularly use medication for seizures, tuberculosis, or HIV/AIDS. Certain other medicines can make levonorgestrel less effective.

Before taking this medicine

You should not use Plan B One-Step if you are allergic to levonorgestrel.

Do not use this medicine if you are already pregnant. Plan B One-Step will not terminate a pregnancy that has already begun (the fertilized egg has attached to the uterus).

Ask a doctor or pharmacist before taking levonorgestrel if you regularly use medication for seizures, tuberculosis, or HIV/AIDS. Certain medications can make levonorgestrel less effective as an emergency form of contraception.

Levonorgestrel may slow breast milk production. Tell your doctor if you are breast-feeding.

How should I take Plan B One-Step?

Use Plan B One-Step exactly as directed on the label, or as prescribed by your doctor.

Plan B One-Step must be taken as soon as possible after unprotected sex (no later than 72 hours afterward).

Call your doctor right away if you vomit within 2 hours after taking this medicine.

Visit your doctor within 3 weeks after taking Plan B One-Step. A doctor should confirm that you are not pregnant, and that this medicine has not caused any harmful effects.

If your period is late by 1 week or longer after the expected date, you may be pregnant. Get a pregnancy test and contact your doctor if you are pregnant. Levonorgestrel will not terminate pregnancy if the fertilized egg has attached to the uterus.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Since Plan B One-Step is used as a single dose, it does not have a daily dosing schedule.

What happens if I overdose?

Because this medicine is supplied as a single tablet in an exact strength, an overdose is unlikely to occur when this medicine is used as directed. Do not take more than one tablet at the same time.

What to avoid

Plan B One-Step will not protect you from sexually transmitted diseases--including HIV and AIDS. Using a condom is the only way to protect yourself from these diseases. Avoid having unprotected sex.

Plan B One-Step side effects

Get emergency medical help if you have signs of an allergic reaction to Plan B One-Step: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor or seek emergency medical help if you have severe pain in your lower stomach or side. This could be a sign of a tubal pregnancy (a pregnancy that implants in the fallopian tube instead of the uterus). A tubal pregnancy is a medical emergency.

Common Plan B One-Step side effects may include:

• stomach pain;

• breast pain or tenderness;

• nausea, vomiting, diarrhea;

• headache, dizziness;

• feeling tired; or

• changes in your menstrual periods.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Plan B One-Step?

Certain other medications can make levonorgestrel less effective, which may result in pregnancy. Do not take this medicine without telling your doctor or pharmacist that you are using any of the following medications:

• efavirenz (Atripla, Sustiva);

• rifampin (Rifadin, Rifater, Rifamate, IsonaRif, Rimactane); or

• seizure medication--carbamazepine, felbamate, fosphenytoin, phenobarbital, phenytoin, primidone.

This list is not complete. Other drugs may interact with levonorgestrel, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Frequently asked questions

• Mirena, Kyleena, Skyla & Liletta - What's the difference?

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Plan B One-Step only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

Copyright 1996-2022 Cerner Multum, Inc. Version: 3.04.