If one breast has returned milk, if the other breast can satisfy the baby’s milk supply, it can be left untreated. If the other breast cannot satisfy the baby’s demand, try to promote the breast that has returned milk to lactate again. If you want to make this side of the breast to continue to lactate, you can let the baby suck on this side of the breast when hungry, to stimulate the mammary glands to be able to secrete milk, and then suck on the other side of the breast, so that the baby can eat. In addition, you can massage the other breast to ease the blockage of the mammary glands and facilitate milk secretion. When stimulating the breast to lactate, you should also make sure that the normal side of the breast is lactating, so as not to let the normal side of the breast lactate as well. Of course, if one side of the milk is enough for the baby’s needs, the other side of the breast can be treated without special treatment.