Can I have a bath 3 weeks post op breast reduction surgery?

At three weeks post op, your wounds should be completely healed, and it should be safe to have a bath. Please always double check with your surgeon, as we all have different postoperative approaches. 

Each surgeon will have his or her own protocol for postop care and bathing, so you really need to check with your own surgeon or his or her nurse for specific instructions in your case.  However, I can tell you how I manage my own patients.  I allow them to shower during the first week after surgery, and until all of the scabs and crusts are gone from the incisions and all wounds are completely covered with the new, pink epidermal skin, I tell them running water only.  Thus, no dunking the breasts in bathtubs, hot tubs, swimming pools, lakes, oceans, or any other standing water until healed.  If my patients want to sit in a bathtub up to their waists and bathe their lower bodies or simply soak their lower bodies, that's fine, as long as the wounds themselves aren't submerged until all scabs and crusts are gone.  This just helps to prevent any bacteria from getting under scabs where some absorbable suture material might still be accessible and cause an infection.  Hope this helps, but again, please call your surgeon to be sure of his or her recommendations first.