The main reasons breasts might hurt and feel heavy include hormonal changes (such as those during the menstrual cycle), fibrocystic breast changes (fluid- filled cysts causing swelling), pregnancy, breastfeeding engorgement, certain medications, infections like mastitis, and rarely, inflammatory breast cancer. Hormones like estrogen and progesterone can cause breast tissue to swell, leading to heaviness and pain, often worsening before a period. Breastfeeding can cause fullness and heaviness, and infections may cause pain, warmth, and redness. Large or heavy breasts can also lead to discomfort including pain. Typically, heavy and painful breasts are not a sign of cancer, but if accompanied by other symptoms, a doctor should be consulted.

If the breast pain and heaviness are new, worsening, or accompanied by other symptoms like lumps, redness, or nipple changes, medical advice should be sought for evaluation.