Letrozole is a medication that often leads to questions about its effects on the menstrual cycle. Understanding how this medication works clarifies its influence on menstruation.
Understanding Letrozole
Letrozole is classified as an aromatase inhibitor, functioning by blocking the enzyme aromatase. This enzyme converts androgens (male hormones) into estrogens. Inhibiting aromatase effectively reduces estrogen production.
This medication is primarily used for hormone-receptor-positive breast cancer, especially in postmenopausal women, where estrogen can fuel cancer cell growth. Letrozole is also widely used off-label as a fertility treatment, particularly for inducing ovulation in individuals with polycystic ovary syndrome (PCOS) or unexplained infertility. For fertility, this temporary estrogen reduction prompts the body to produce hormones that stimulate egg development.
Letrozole’s Impact on the Menstrual Cycle
Letrozole directly influences the menstrual cycle by significantly lowering estrogen levels. Estrogen regulates the ovulatory process and the shedding of the uterine lining, resulting in menstruation. When letrozole inhibits aromatase, the reduced estrogen can disrupt this hormonal balance.
This disruption can lead to various menstrual changes, including periods stopping entirely (amenorrhea), becoming lighter, or occurring irregularly. The specific effect often depends on the dosage and the reason for taking letrozole; for instance, higher doses for cancer treatment may result in more profound and consistent estrogen suppression compared to lower, cyclical doses for fertility. For fertility, this temporary estrogen drop triggers a surge in follicle-stimulating hormone (FSH), stimulating the ovaries to develop and release an egg, potentially leading to ovulation and a subsequent period.
Navigating Menstrual Changes and Other Considerations
Individuals taking letrozole may experience changes in their menstrual patterns, including lighter flow, irregular cycles, or missed periods. These variations directly result from the medication’s effect on estrogen levels. If a period is missed, particularly when taking letrozole for fertility, it is important to perform a pregnancy test.
Common side effects of letrozole, often due to reduced estrogen, include hot flashes, joint pain, and fatigue. While these effects are typically manageable, unexpected bleeding or a missed period should be discussed with a healthcare provider. Consulting a doctor is also important if there are concerns about potential pregnancy or if side effects become bothersome, as individual responses to letrozole can vary.