The Core Question: Plan B vs. Levonorgestrel
When seeking emergency contraception (EC), a common point of confusion is the difference between Plan B and levonorgestrel. The simple answer is that there is no medical difference. Plan B One-Step is the well-known brand name for a single-dose pill containing 1.5 mg of levonorgestrel [1.2.1, 1.2.2]. Levonorgestrel is the active ingredient, a synthetic hormone (progestin) that does the work of preventing pregnancy [1.2.5]. Many other generic versions of this pill exist under names like Take Action, My Way, Aftera, and Preventeza, and they are all medically identical to Plan B [1.3.2, 1.8.3]. The question of 'which is better' really becomes a comparison between the brand name and its generic equivalents.
What is Levonorgestrel and How Does It Work?
Levonorgestrel is a progestin hormone that has been used in birth control pills for decades [1.5.3]. As an emergency contraceptive, its primary mechanism is to prevent or delay ovulation, which is the release of an egg from the ovary [1.2.1, 1.4.5]. If intercourse occurs but an egg is not released, fertilization cannot happen. It may also prevent fertilization by affecting sperm or the egg [1.2.1]. It is crucial to understand that levonorgestrel is not an abortion pill; it does not harm or terminate an existing pregnancy [1.2.1, 1.6.5].
The Real Comparison: Branded vs. Generic
The most significant difference between Plan B One-Step and generic levonorgestrel pills is cost [1.3.1]. As the original, heavily marketed product, Plan B is typically more expensive.
| Feature | Plan B One-Step | Generic Levonorgestrel (e.g., Take Action, My Way) |
|---|---|---|
| Active Ingredient | 1.5 mg Levonorgestrel [1.2.2] | 1.5 mg Levonorgestrel [1.3.1] |
| Effectiveness | 75-89% effective if taken within 72 hours [1.3.1]. | 75-89% effective if taken within 72 hours [1.3.1]. |
| Dosage | One single pill [1.3.1]. | One single pill [1.3.1]. |
| Typical Cost | $40 - $50 [1.3.1, 1.3.4]. | $10 - $40 [1.3.3]. |
| Availability | Over-the-counter at most pharmacies and superstores without a prescription or age limit [1.2.1, 1.9.3]. | Over-the-counter, but may be slightly less widespread than Plan B. Available online and at major retailers [1.3.2]. |
Effectiveness and Timing: The Critical Window
All levonorgestrel-based emergency contraception pills are most effective the sooner they are taken after unprotected sex [1.2.1]. The effectiveness is highest when taken within 24 hours and decreases with time [1.5.5]. While it is approved for use up to 72 hours (3 days), it can be taken up to 120 hours (5 days) after intercourse, though its efficacy is lower at that point [1.4.5]. If taken within 72 hours, it can reduce the risk of pregnancy by up to 89% [1.5.5].
Factors That Can Influence Effectiveness
Body weight and Body Mass Index (BMI) may impact how well levonorgestrel works. Some studies suggest that its effectiveness may be reduced in individuals who weigh over 165 pounds (75 kg) or have a BMI over 25-30 [1.7.3, 1.4.5]. In these cases, other emergency contraception options might be more effective [1.7.3].
Potential Side Effects
Side effects are generally mild and temporary for all levonorgestrel pills. The most common side effects include [1.6.2, 1.6.4]:
- Changes in your next menstrual period (it may be earlier, later, heavier, or lighter)
- Nausea
- Lower abdominal pain or cramps
- Headache
- Fatigue
- Dizziness
- Breast tenderness
If you vomit within two hours of taking the pill, you should contact a healthcare professional to see if you need to take another dose [1.10.1].
Alternatives to Levonorgestrel
If it has been more than 72 hours since unprotected sex or if weight is a concern, there are other EC options:
- Ella (ulipristal acetate): This is a different type of pill that is effective for up to 120 hours (5 days) after intercourse and is considered more effective than levonorgestrel, especially for those with a higher BMI [1.8.4]. Ella requires a prescription in the United States [1.8.4].
- Copper IUD (ParaGard): This is the most effective form of emergency contraception, with an effectiveness rate of over 99% [1.9.1]. A healthcare provider must insert it within 5 days of unprotected sex, and it can then serve as long-term birth control for up to 12 years [1.5.3, 1.8.2].
Conclusion: Making the Best Choice
Deciding between Plan B and a generic levonorgestrel pill comes down to personal preference, cost, and what's immediately available [1.3.2]. Since they are medically the same, the most cost-effective generic option will work just as well as the brand-name product [1.4.5]. The most critical factor for success is taking the pill as soon as possible after unprotected sex. It is also important to remember that EC pills do not protect against sexually transmitted infections (STIs) [1.4.4].
For more information, you can visit Planned Parenthood.
