Is It normal to have brown discharge after 10 days of breast reduction surgery?

Thank you very much for sharing your concerns with us. Ten days after Breast Reduction, it's not time enough to express a valid opinion of results.On the other hand, generally to avoid the normal p.o. swelling, I recommend to limit the arms movement for two weeks. Also it's not advisable to carry weight and take the antiinflamatory painkillers drugs.Finally, I recommend you always use a therapeutic bra.Respectfully,Dr. Emmanuel Mallol Cotes.- 

Brown leakage can be old blood,or seroma fluid as the likely sources. Best to see your doctor for appropriate management. 

Brown discharge usually represents some old blood from surgery that has liquefied and drains out but 10 days is a little early for this. You seem to be very active so I doubt anything too bad is going on, also since the amount of drainage is low. I would touch bases with your plastic surgeon to be on the safe side.