Swollen and painful eyelids are caused by three main reasons: First, they are caused by mydriasis, a painful swollen eyelid that is usually limited in location and can be felt as a nodule under the skin, and is caused by a bacterial infection of the lid gland due to poor eye hygiene habits, such as rubbing the eye with the hand. Second, it is caused by cellulitis of the eyelid, which is associated with low body resistance, trauma to the eyelid area, or extrusion of the lentigo. The main manifestation is redness and pain throughout the eyelid, accompanied by fever and swollen lymph nodes in front of the ear. Thirdly, ulcerative blepharitis is caused by a swollen eyelid, usually located at the edge of the eyelid or at the root of the eyelashes, and is accompanied by loss of eyelashes and local skin ulcers.