Redness and swelling of the lower eyelid in children may be caused by acute injury, infectious factors, allergic factors and so on. 1. Acute injury: If children’s lower eyelids are struck by external forces, resulting in localized damage, the lower eyelids will appear red, swollen, and there may be subcutaneous bruising, obvious pain and other symptoms of discomfort. 2. Infectious factors: Infectious conjunctivitis, blepharitis and other eye infections, usually associated with bacterial or viral infections, under the stimulation of inflammation, the patient may appear red and swollen eyelids and other symptoms, which may also be accompanied by photophobia, tearing and other symptoms. 3. Allergic factors: If allergic children come into contact with allergenic substances, such as pollen and dust, and have an allergic reaction, they may have symptoms such as redness and swelling of the lower eyelids, accompanied by itching of the eyes. It is recommended that children with obvious redness and swelling of the lower eyelids seek medical attention to assess their condition and follow medical advice.