Plan B Dosage

Unlike the original version of Plan B (containing two tablets taken 12 hours apart), Plan B One-Step is taken as a single dose. To help avoid an upset stomach, you may want to take your Plan B dose(s) with food. If you vomit within an hour of taking this medication, contact your healthcare provider for further instructions.

Plan B Dosage: An Introduction

There is only one standard dosage for Plan B One-Step™ (levonorgestrel), regardless of your age or weight. As always, do not adjust this dose unless your healthcare provider specifically tells you to do so.

Plan B One-Step Dosage for Emergency Contraception

Plan B One-Step comes in a pack of just one tablet. It is taken as a single dose as soon as possible within 72 hours (three days) after unprotected sex. The sooner you take it, the more effective it is at preventing pregnancy.

Original Plan B Dosage for Emergency Contraception

Plan B originally came as a two-step formulation, which has since been discontinued, but is still available in generic form. The old Plan B came in a pack of two tablets. The first tablet should be taken as soon as possible within 72 hours (three days) after unprotected sex. The second tablet should be taken 12 hours after the first tablet, even if this means taking it in the middle of the night. The sooner you take it, the more effective it is at preventing pregnancy.

General Information on Your Plan B Dosage

Some considerations for women using Plan B include the following:
  • While it is not necessary to take Plan B with food, doing so can help prevent stomach upset.
  • If you vomit within one hour of taking a dose of Plan B, call your healthcare provider immediately to see if you should repeat the dose.
  • Plan B should not be used as your main form of birth control, because other methods of birth control are usually much more effective.
  • For the medication to work properly, it must be taken as prescribed.
  • If you are unsure about anything related to your Plan B dosage, please talk to your doctor, nurse, or pharmacist.
Last reviewed by: Kristi Monson, PharmD
Pregnancy and Pain