Does tamoxifen cause period changes? Should I worry?

Menstrual cycle changes are a common side effect of tamoxifen, and fluctuations in cycle length and flow can happen throughout treatment rather than following a predictable pattern. These variations don't necessarily indicate that the medication isn't working effectively - tamoxifen's cancer-fighting benefits work differently than its effects on menstrual cycles. It's completely understandable to feel concerned about these changes, so discussing them with your oncologist can provide reassurance and help determine if any monitoring or adjustments are needed.