Why do my breasts hurt before my period?

Cyclical breast pain, tender, heavy, both sides, worst in the week before bleeding, is a hormone effect on breast tissue and affects most women at some point. It fades as the period arrives.

A well-fitted supportive bra, cutting late-cycle caffeine, and simple pain relief cover most of it.

Different rules for different pain: a new lump, one-sided persistent pain, skin changes, nipple discharge or any breast change after menopause is not cyclical territory and needs examination promptly. Lumpiness that comes and goes with the cycle is common; a lump that persists through a full cycle is the one to show a doctor.