How is Plan B (levonorgestrel) taken?

How to Take Plan B (Levonorgestrel)

Plan B should be taken as a single 1.5 mg tablet as soon as possible within 72 hours (3 days) after unprotected intercourse or contraceptive failure, with earlier administration providing better effectiveness. 1

Administration Details

• Plan B (levonorgestrel) is available as:

  • A single 1.5 mg tablet (Plan B One-Step)
  • Two 0.75 mg tablets (generic versions) that can be taken together as a single dose 2, 1

• No prescription is required:

  • Plan B One-Step is FDA-approved as a nonprescription product for all women of childbearing potential
  • Generic versions are approved as nonprescription for women 17 years and older (though proof of age is not required to purchase) 2

Timing and Effectiveness

• Timing is critical: The sooner Plan B is taken after unprotected sex, the more effective it is 1
• While most effective within 72 hours, it can be taken up to 5 days (120 hours) after unprotected intercourse 2, 3
• Effectiveness:
  • Prevents approximately 75-80% of expected pregnancies when taken correctly 3
  • About 7 out of 8 women who would have gotten pregnant will not become pregnant 1

What to Do If Vomiting Occurs

• If vomiting occurs within 2 hours of taking Plan B, contact a healthcare professional to determine if the dose should be repeated 1

Special Considerations

• Weight considerations: Plan B may lose effectiveness in women who weigh more than 165 pounds and may be ineffective in women who weigh more than 176 pounds 2
• Medication interactions: Effectiveness may be reduced if taking:
  • Efavirenz (HIV medication)
  • Rifampin (tuberculosis treatment)
  • Medications for seizures/epilepsy 1

Common Side Effects

• Changes in menstrual cycle (heavier/lighter or early/late period)
• Nausea
• Lower abdominal pain
• Tiredness
• Headache
• Dizziness
• Breast tenderness 1

Important Warnings

• Plan B will not work if you are already pregnant and will not affect an existing pregnancy
• It will not protect against HIV/AIDS or other sexually transmitted diseases
• It should not be used as a regular form of birth control as it is less effective than other contraceptive methods 1, 3
• Seek immediate medical attention if experiencing severe abdominal pain, as this could indicate an ectopic pregnancy 1

How to Know If It Worked

You will know Plan B has been effective when you get your next period, which should come at the expected time or within a week of the expected time. If your period is delayed more than a week, take a pregnancy test and follow up with your healthcare provider 1.