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Plan B

Last reviewed on RxList: 7/28/2020
Plan B Side Effects Center

What Is Plan B?

Plan B (levonorgestrel, also known as the "Morning After Pill") is a female hormone that prevents ovulation used an emergency contraceptive 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 is available in generic form.

What Are Side Effects of Plan B?

Common side effects of Plan B include:

  • nausea,
  • vomiting,
  • abdominal or stomach pain,
  • tiredness,
  • dizziness,
  • changes in menstrual periods,
  • breast pain or tenderness,
  • diarrhea, or
  • headache.

Tell your doctor right away if you have any serious side effects of Plan B including:

  • severe lower stomach pain (especially 3 to 5 weeks after taking Plan B).

Dosage for Plan B

One tablet of Plan B should be taken orally as soon as possible within 72 hours after unprotected intercourse. The second tablet should be taken 12 hours after the first dose.

What Drugs, Substances, or Supplements Interact with Plan B?

Plan B may interact with rifampin, barbiturates, or seizure medicines. Other drugs may affect Plan B emergency contraceptive. Tell your doctor all prescription and over-the-counter medications you use.

Plan B During Pregnancy and Breastfeeding

Plan B should not be used during pregnancy. If you become pregnant or think you may be pregnant, inform your doctor immediately. This medication passes into breast milk. Though there have been no reports of harm to nursing infants, consult your doctor before breastfeeding.

Additional Information

Our Plan B (levonorgestrel) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

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.

QUESTION

Which of the following are methods for contraception? See Answer
Plan B Consumer Information

Get emergency medical help if you have signs of an allergic reaction: 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 side effects may include:

  • mild 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.

Read the entire detailed patient monograph for Plan B (Levonorgestrel Emergency Contraception, Morning After Pill)

SLIDESHOW

Choosing Your Birth Control Method See Slideshow
Plan B Professional Information

SIDE EFFECTS

Clinical Trial Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

A double-blind, controlled clinical trial in 1,955 evaluable women compared the efficacy and safety of Plan B (one 0.75 mg tablet of levonorgestrel taken within 72 hours of unprotected intercourse, and one tablet taken 12 hours later) to the Yuzpe regimen (two tablets each containing 0.25 mg levonorgestrel and 0.05 mg ethinyl estradiol, taken within 72 hours of intercourse, and two tablets taken 12 hours later).

The most common adverse events (>10%) in the clinical trial for women receiving Plan B included menstrual changes (26%), nausea (23%), abdominal pain (18%), fatigue (17%), headache (17%), dizziness (11%), and breast tenderness (11%). Table 1 lists those adverse events that were reported in ≥5% of Plan B users.

Table 1: Adverse Events in ≥5% of Women, by % Frequency

  Plan B
Levonorgestrel
N=977 (%)
Nausea 23.1
Abdominal Pain 17.6
Fatigue 16.9
Headache 16.8
Heavier Menstrual Bleeding 13.8
Lighter Menstrual Bleeding 12.5
Dizziness 11.2
Breast Tenderness 10.7
Vomiting 5.6
Diarrhea 5.0

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of Plan B. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Gastrointestinal Disorders

Abdominal Pain, Nausea, Vomiting

General Disorders and Administration Site Conditions

Fatigue

Nervous System Disorders

Dizziness, Headache

Reproductive System and Breast Disorders

Dysmenorrhea, Irregular Menstruation, Oligomenorrhea, Pelvic Pain

Read the entire FDA prescribing information for Plan B (Levonorgestrel Emergency Contraception, Morning After Pill)

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