You can wash your hair only after a week after your head has been bumped. After your head has been bumped, you need to cut off the hair from the bumped area and have the wound cleaned and sutured. If the stitches are very good and tight, and there is no local defect, the stitches can be removed after five days, and you can wash your hair after two days to a week. However, you should not wash your hair for too long. Soaking your scalp in water for too long may lead to redness, inflammation and pain. If there is a defect in the scalp and the suture is not very tight, the wound may take longer to heal, usually about a week. Observe the healing of the wound, intermittently remove the stitches if necessary, and only after the wound has healed can the stitches be completely removed. The time for washing hair should also be extended, if necessary until about two weeks.