Redness of the lower eyelids in infants is usually considered to be caused by external friction, allergic reactions, insect bites or wheals. 1. External friction: When infants rub their eyes hard, it is easy to produce excessive irritation to the eyes, causing redness of the lower eyelids. 2. Allergic reaction: when there is an allergen stimulation effect and cause allergic reaction of the baby’s skin, resulting in redness of the lower eyelid, or even erosion, oozing and so on. 3. Mosquito bites: If an infant is bitten by a mosquito, there is usually a transient redness of the lower eyelid. 4. Emphysema: If an infant has emphysema due to acute inflammation of the sebaceous glands or blepharoplakic glands in the lower eyelid, it may also show redness and congestion of the lower eyelid, and may be accompanied by fever, pain and other symptoms. In conclusion, the causes of lower eyelid redness in infants are complex, and it is important to go to the hospital in a timely manner to determine the cause of the problem and then take targeted treatment.