Itchy, red and swollen eyelids may be caused by skin allergy, mosquito bites and blepharitis. 1. Skin allergy: patients with allergies can have allergic reactions when they come into contact with allergens, such as dust, pollen, cosmetics, skin care products, etc., which can cause itchy, red and swollen eyelids and other uncomfortable symptoms. 2. Mosquito bites: patients whose eyelids have been bitten by external mosquitoes will also experience itching, redness and swelling of the eyelids. 3. Blepharitis: Due to lack of hygiene or low immunity, bacterial infections can cause localized suppurative inflammation of the eyelids, leading to itchy, red and swollen eyelids. It is recommended that patients with itchy, red and swollen eyelids consult a doctor to evaluate their condition and follow the doctor’s instructions for treatment.