What is the cause of milk dropping from the breast, especially when the lady is not pregnant?

Galactorrhea...: Is the medical name for milky nipple discharge not associated with pregnancy. Can be associated with hormone imbalance, particularly, prolactin, and some diseases which affect it. It can also be a side effect of some medications for blood pressure, depression or birth control pills. Some natural herbs can cause as well. If it persists, you should see a doctor for an evaluation.

Check prolactin: The breast is under hormonal control relative to milk production. If you have constant leaking from your breasts, checking a prolactin level might be in order. This could signal a problem with your pituitary gland. If the leakage is just from one side, a breast exam and possible mammogram might be indicated. Either way, see you doctor for follow up.