The reasons for the darkening of the skin on the back of the hand and tiger’s mouth usually include hyperpigmentation and bruising, which need to be treated as soon as they are found. 1. Hyperpigmentation: The darkening of the skin on the back of the hand and tiger’s mouth may be related to the local skin inflammation left behind hyperpigmentation, which can be moisturized by applying vitamin E ointment to lighten the color of the sedimentation, but also for laser treatment. 2. Bruising: the back of the hand tiger’s mouth skin blackened may also be traumatic capillary rupture caused by bruising, the patient can be through hot compresses or massage methods to a certain extent to improve the symptoms, if there is no significant change in the need to go to the hospital in a timely manner in order to clarify the cause of the examination. The back of the hand tiger’s mouth skin blackening causes more, it is recommended to go to the hospital.