Plan B, also known as levonorgestrel emergency contraception, is a medication designed to prevent pregnancy following unprotected sexual intercourse or contraceptive failure. Its primary role is to act as a backup method, not a regular form of birth control. A common concern for individuals who use this medication involves its potential impact on their menstrual cycle.
How Plan B Works to Affect the Cycle
Plan B contains a high dose of levonorgestrel, a synthetic hormone similar to the progesterone naturally produced by the body. It works by interfering with the hormonal balance that regulates the menstrual cycle, specifically by preventing or delaying the release of an egg from the ovary, a process known as ovulation. If ovulation has not yet occurred, the medication can disrupt the luteinizing hormone (LH) surge, which is essential for egg release.
By preventing or postponing ovulation, Plan B prevents sperm from fertilizing an egg, thereby averting pregnancy. The effectiveness of Plan B is highest when taken as soon as possible after unprotected sex, generally within 72 hours, though it can be used up to 120 hours. If ovulation has already happened, Plan B is less likely to be effective because its primary mechanism of action has been bypassed.
Expected Changes to Your Menstrual Cycle
Taking Plan B can alter an individual’s menstrual cycle due to its hormonal impact, with many people experiencing spotting or light bleeding between their expected periods. This intermenstrual bleeding is a common response to the hormonal shifts induced by the medication.
The timing of the next period can also be affected, with some individuals experiencing it earlier or later than anticipated, sometimes by up to a week. Changes in menstrual flow are also possible; some report a period that is heavier or lighter than their usual flow, and the duration of bleeding might vary. These variations are generally considered normal side effects as the body adjusts to the temporary hormonal changes.
Duration of Cycle Changes
For most individuals, any disruptions to the menstrual cycle caused by Plan B are temporary. The menstrual cycle typically returns to its regular pattern within one to two cycles following the use of the medication. This means that while the first period after taking Plan B might be different, subsequent cycles are likely to resemble the individual’s usual pattern.
The exact duration of these changes can vary from person to person, influenced by factors such as when in the menstrual cycle Plan B was taken. For instance, taking the medication earlier in the cycle might lead to an earlier next period, while taking it later could result in a delayed period.
When to Seek Medical Advice
While menstrual changes after taking Plan B are common, certain situations warrant medical attention. Consult a healthcare provider if your period is delayed by more than a week beyond its expected date, as this could indicate a pregnancy despite taking the medication. A pregnancy test is recommended in such cases.
Medical consultation is also important for severe abdominal pain, especially if it occurs three to five weeks after taking Plan B, as this could be a sign of an ectopic pregnancy. Additionally, unusual or very heavy bleeding that persists, or any other severe or lingering symptoms, should prompt a visit to a healthcare professional. Persistent irregularities in subsequent cycles also warrant evaluation to rule out other underlying causes.