Plan B Side Effects

Levonorgestrel is a female hormone that prevents ovulation (the release of an egg from an ovary). Plan B also causes changes in your cervical mucus and uterine lining, making it harder for sperm to reach the uterus and harder for a fertilized egg to attach to the uterus. Learn more about the Plan B Side Effects below.

Plan B 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 may also be used for other purposes not listed in this medication guide.

Get emergency medical help if you have any of these signs of an allergic reaction to Plan B: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once 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.

Plan B should be used exactly as described on the label of the box. Do not take smaller or larger doses then what is recommended on the box.  The first dose should be taken as soon as possible after unprotected sex occurs. No later than 72 hours afterwards.

If you vomit within 1 hour after taking the dose of Plan B you should immediately contact your doctor right away. Do not take another dose until you have spoken with your doctor.

Additionally you should be examined by your doctor within 3 weeks of taking the pill to make sure everything is going as expected.

If your period is late by one week or longer it is possible that you may be pregnant. At this point you should contact your doctor and take a pregnancy test.

Make sure that you store Plan B away from heat and moisture and at room temperature.

Plan B Side Effects include:

  • nausea, diarrhea, or stomach pain
  • breast pain or tenderness
  • dizziness, tired feeling
  • changes in your menstrual periods
  • headache

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about plan b side effects.