Redness under the eyelids of children may be caused by eyelid hematoma, blepharitis, conjunctivitis and other reasons. 1. Eyelid hematoma: Eyelid hematoma is often caused by trauma to the patient’s eyelid and rupture of subcutaneous blood vessels in the eyelid. If not treated in time or fully recovered, the patient is prone to subcutaneous accumulation of blood leading to eyelid hematoma, which causes redness, pain, swelling and other uncomfortable symptoms in the lower eyelid. 2. Blepharitis: Blepharitis refers to suppurative inflammation of the eyelid glands. Under the stimulation of inflammation, the patient’s eyelids may appear obvious redness and swelling, accompanied by pressure and pain, burning sensation and other uncomfortable symptoms. 3. Conjunctivitis: Conjunctivitis can be triggered by allergic reactions or external stimuli such as mosquito bites. In addition to the redness and swelling of the lower eyelids, patients are often accompanied by itchy eyes, increased secretions and other discomforts. It is recommended that patients with obvious redness and swelling of the lower eyelids consult a doctor in a timely manner to assess their condition and follow the doctor’s instructions for treatment.