Understanding Plan B and Other Emergency Contraceptives: A Comprehensive Guide

Understanding Plan B and Other Emergency Contraceptives: A Comprehensive Guide

Emergency contraception is a critical tool for preventing unwanted pregnancy after unprotected intercourse or contraceptive failure. Plan B and its equivalents are the most common forms of emergency contraception. Here's what you need to know about them and how they work.

What are Emergency Contraceptives?

  1. Levonorgestrel-Based Pills (e.g., Plan B): These are over-the-counter emergency contraceptive pills containing levonorgestrel, a synthetic progestin. Brands include Plan B One-Step, Take Action, My Way, and others. They work by delaying ovulation and are most effective when taken as soon as possible after unprotected sex, ideally within 3 days, but they can be used up to 5 days afterward. Their efficacy decreases with time and may be reduced in individuals weighing more than 165 pounds.

  2. Ulipristal Acetate (e.g., Ella): Ella is a prescription-only emergency contraceptive pill. It's more effective than levonorgestrel pills, especially when taken later (3-5 days after unprotected sex). Weight does not seem to affect its efficacy as much as it does with levonorgestrel pills.

  3. Copper IUD: This is a non-hormonal option and the most effective form of emergency contraception. It needs to be inserted by a healthcare provider within 5 days after unprotected sex.

How Do They Work?

  • Levonorgestrel Pills: These pills prevent pregnancy primarily by delaying ovulation. They do not terminate an existing pregnancy.

  • Ulipristal Acetate: This works by preventing ovulation and possibly by making it harder for a fertilized egg to implant in the uterus.

  • Copper IUD: It works by creating an inflammatory reaction toxic to sperm and eggs, preventing fertilization and implantation.

Side Effects and Precautions

  • Common Side Effects: These can include changes in menstrual bleeding, headaches, nausea, and abdominal pain. Levonorgestrel causes less nausea and vomiting than older, combined estrogen-progestin pills.

  • Weight Considerations: Levonorgestrel pills might be less effective in individuals over 165 pounds. In such cases, ulipristal acetate or a copper IUD might be better options.

  • Medication Interactions: Certain medications, like the antibiotic Rifampin, can reduce the effectiveness of levonorgestrel pills.

Regular Use and Long-term Effects

  • Not for Regular Use: These methods are designed for emergency situations and not as regular birth control because of their lower effectiveness compared to standard contraceptive methods and the potential for side effects.

  • After Use: You can generally start or resume regular birth control immediately after using emergency contraception. However, if using ulipristal acetate, it's advisable to wait a few days before starting hormonal contraceptives.

  • Repeated Use: While it's safe to use emergency contraceptives more than once, they should not be relied upon as a regular contraceptive method due to lower effectiveness and potential side effects.

Availability and Cost

  • Over-the-Counter Availability: Levonorgestrel-based pills are available without a prescription. Prices vary, with generics typically being more affordable.

  • Prescription Options: Ella (ulipristal acetate) requires a prescription.

  • Insurance Coverage: Health insurance or Medicaid may cover these costs, and some clinics may offer them for free or at a reduced cost.


In summary, while emergency contraceptives like Plan B are a crucial option for preventing unintended pregnancies, they are not substitutes for regular contraception methods. Their effectiveness varies based on timing, individual factors like weight, and potential interactions with other medications. Always consult a healthcare provider for personalized advice, especially when considering using emergency contraception or starting a regular contraceptive method afterward.

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