A finger suddenly swollen and itchy, mainly due to external mosquito bites, mosquito bites will be injected into the body toxic chemicals, resulting in local allergic reactions to the location, tissue fluid exudation increased, so there will be local swelling, in addition to local stimulation of peripheral nerves, there will also be local itchy situation. When this happens, do not scratch excessively, otherwise it may lead to skin breakage, causing viral or bacterial infection, which is not conducive to wound healing. And to apply local dexamethasone acetate cream, take poisonous Kang and other drugs, can effectively anti-allergic, anti-inflammatory reaction, can effectively reduce local edema and peripheral nerve stimulation, local swelling and itching can be effectively relieved.