From the FDA Drug Label
some women may have changes in their period, such as a period that is heavier or lighter or a period that is early or late. Side effects may include changes in your period, nausea, lower stomach (abdominal) pain, tiredness, headache, dizziness, and breast tenderness The Plan B pill, also known as levonorgestrel, may cause bleeding as a side effect, including changes in menstrual bleeding, such as heavier or lighter periods, or earlier or later periods 1. It is essential to note that these changes are a possible side effect of the medication. If you experience severe abdominal pain or a delayed period, you should seek medical attention to rule out pregnancy or other complications 1.
From the Research
Plan B (levonorgestrel) can cause bleeding or spotting in some women, and the most recent and highest quality study suggests that the prevalence of adverse events, including bleeding, is not statistically different between different dosing regimens 2. When considering the potential effects of Plan B on menstrual bleeding, it's essential to weigh the benefits and risks. The medication works by delaying or preventing ovulation, which can disrupt the regular menstrual cycle and lead to irregular bleeding or spotting. Some key points to consider include:
- The hormonal change caused by Plan B can affect the uterine lining, leading to unexpected bleeding 2.
- The most common adverse effects of levonorgestrel are not serious, but they can include bleeding or spotting 2.
- If you experience extremely heavy bleeding, severe abdominal pain, or if bleeding continues for more than a week after taking Plan B, you should contact a healthcare provider.
- Most bleeding side effects resolve on their own as your hormonal cycle returns to normal, typically by your next menstrual period. It's also important to note that the evidence on the adverse effects of levonorgestrel emergency oral contraceptives is based on a systematic review and meta-analysis of multiple studies, including randomized controlled trials and observational studies 2. However, the study that provides the most relevant information on the topic is the one published in 2020 in the Clinical Drug Investigation journal, which found that the prevalence of adverse events, including bleeding, was not statistically different between different dosing regimens 2. Therefore, the most appropriate course of action is to take Plan B as directed and monitor for any adverse effects, including bleeding, and seek medical attention if necessary.