How Birth Control Pills and Plan B Function
To understand why the pill and Plan B do not cancel each other out, it is important to first examine how each form of contraception works independently. While both contain synthetic hormones, their dosage and purpose are distinct.
The Mechanism of Daily Birth Control Pills
Regular birth control pills, such as combination pills, contain consistent, low doses of synthetic estrogen and progestin. They prevent pregnancy primarily in three ways:
- Preventing ovulation: The hormones stop your ovaries from releasing an egg each month.
- Thickening cervical mucus: This makes it more difficult for sperm to travel through the cervix to reach an egg.
- Thinning the uterine lining: This makes it more difficult for a fertilized egg to implant in the uterus.
The Mechanism of Plan B Emergency Contraception
Plan B One-Step and its generic equivalents contain a single, high dose of the hormone levonorgestrel, a progestin. This medication is intended for emergency use after unprotected sex or contraceptive failure, like a missed pill. Its primary mechanism of action is delaying or preventing ovulation. If ovulation has already occurred, Plan B is not effective and cannot terminate an existing pregnancy. The effectiveness of Plan B is highest when taken as soon as possible after unprotected sex, and decreases over time.
The Interaction: Do the Pill and Plan B Cancel Each Other Out?
The simple answer is no, the pill and Plan B (levonorgestrel) do not cancel each other out. In fact, you should continue your regular birth control regimen after taking Plan B. Taking Plan B introduces a temporary, high dose of hormones into your system to prevent an emergency pregnancy, which acts as a hormonal backup plan. This is not the same as neutralizing the effect of your daily pills. The key is to understand that the two medications, despite using similar hormones, are designed for different purposes and work on different timelines.
The combined hormonal intake will not counteract the effects of either contraceptive method, but it can cause some temporary hormonal fluctuations and side effects. These effects are generally not a cause for concern but highlight that emergency contraception is not a suitable replacement for a consistent, reliable method.
What to Do After Taking Plan B on Your Birth Control
If you have taken Plan B due to a missed pill or another type of contraceptive failure, the recommended course of action is clear:
- Continue taking your regular birth control pill as scheduled, starting immediately. Do not stop taking your daily pill, as this would remove your ongoing protection against pregnancy.
- Use a backup barrier method of contraception, such as condoms, for at least seven days following the use of Plan B. This is critical to ensure you are protected until your regular birth control has fully reestablished its effectiveness, especially after a missed dose.
- Be aware of potential side effects, which can include nausea, breast tenderness, and changes to your next menstrual cycle. The high dose of hormones in Plan B, combined with your regular dose, can sometimes amplify these effects temporarily.
- Take a pregnancy test if your period is delayed by more than one week to confirm the effectiveness of the emergency contraception.
A Critical Exception: The Prescription EC Pill ella
It is crucial to distinguish between levonorgestrel-based Plan B and the prescription-only emergency contraceptive, ella (ulipristal acetate). Unlike Plan B, ella works by blocking the body's progesterone receptors, which can directly interfere with hormonal birth control. Therefore, if you take ella, you must wait at least five days before starting or resuming hormonal contraception and must use a barrier method during that time. Always check the product or consult a healthcare provider to ensure you understand the specific instructions for your emergency contraceptive.
Comparison of Birth Control Pills vs. Plan B
Feature | Regular Birth Control Pills (e.g., Combo Pill) | Plan B (Levonorgestrel) |
---|---|---|
Primary Purpose | Long-term, consistent pregnancy prevention. | Emergency prevention after unprotected sex or contraception failure. |
Dosage | Low, consistent daily dose of hormones. | Single, high dose of a progestin hormone. |
Frequency | Taken daily at the same time. | One-time use per incident. Can be used more than once per cycle, but not recommended as a regular method. |
Key Mechanism | Suppresses ovulation, thickens cervical mucus, thins uterine lining. | Primarily delays or prevents ovulation. |
Timing | Provides continuous protection when taken correctly. | Most effective within 72 hours of unprotected sex, with efficacy decreasing over time. |
Effectiveness | Up to 99% effective with perfect use. | Significantly reduces risk of pregnancy when used promptly. |
Conclusion: Clarity on Combined Contraception
The concern that the pill and Plan B cancel each other out is a common misconception rooted in confusion about how different hormonal contraception methods operate. In reality, Plan B acts as an effective hormonal "booster shot" when taken in response to a contraceptive failure while on your regular birth control, not as an antagonist. The two methods are compatible and serve distinct, though related, purposes. For anyone using or considering emergency contraception, understanding these differences is key to making informed and effective decisions for their reproductive health. Always consult a healthcare provider if you are unsure about what steps to take, particularly regarding the timing and use of backup contraception.
For more information on the mechanisms of Plan B, including how it works and common questions, visit the manufacturer's FAQ page.