Itchy eyelids are common in daily life and can occur in people of all ages. There are many causes of itchy eyelids, including mainly allergic factors and causes of the surrounding living environment, and infectious factors are relatively uncommon. The most common factor is allergy. Localized allergic dermatitis of the eyelids, with allergic reactions to certain medications, foods, eye cosmetics, hair dyes, pollen, or certain dust particles in the air, is the most common symptom of itchy eyelids. Itchy eyelids can also occur in people who are overly tired with their eyes, such as those who stay up late for a long time, often contact with electronic products, or work at close range for a long time, causing eye fatigue, will have the symptoms of itchy eyelids. In addition, there is a very small percentage of itchy eyelids that have no clear cause and are paroxysmal or episodic. Infectious factors causing itchy eyelids are not common, and most are associated with blepharitis and conjunctivitis. In herpes zoster of the eyelid caused by a viral infection, itchy eyelid symptoms can occur during the regressive phase of the lesion due to abnormal skin sensation.