The redness, swelling and itchiness of the patient’s eyelids may be related to mosquito bites, or it may be caused by blepharitis or allergic conjunctivitis. 1. Mosquito bites: Especially in the hot summer, due to the high number of mosquitoes, if the patient’s eyelids are inadvertently bitten by mosquitoes, it may cause the patient’s eyelids to be red, swollen, itchy and other uncomfortable symptoms. This is mainly due to the fact that the toxins in the body are retained in the eyelid skin after the mosquito bites the skin. 2. Blepharitis: Blepharitis refers to suppurative inflammation of the eyelid glands. Under the stimulation of inflammation, patients may experience symptoms such as redness, swelling and itching of the eyelids, which may be accompanied by tearing and eye swelling, especially when blinking, the pain is more obvious. 3. Allergic conjunctivitis: after contact with cosmetics, dust mites, pollen and other substances, allergic patients may cause allergic reactions, triggering allergic conjunctivitis, under the stimulation of inflammation, the patient may have red, swollen and itchy eyes, accompanied by tears, photophobia and other uncomfortable symptoms. It is recommended that patients with red, swollen and itchy eyelids should consult a doctor in time to assess their condition and follow the doctor’s instructions for treatment.