Sudden redness in both eyes of a child is usually caused by infectious conjunctivitis, eye allergy and other reasons. Infectious conjunctivitis is usually due to the child’s poor eye hygiene habits, often with dirty hands rubbing, touching the eyes, etc., the pathogens in the external environment to the eye, triggered by the conjunctival tissue infection caused by the patient in addition to the redness of the eyes, there will be an increase in eye discharge, conjunctival edema and other symptoms of discomfort. Eye allergy is mostly caused by allergic children who are exposed to cotton wool, willow, pollen, smoke, dust, animal hair and other allergens that trigger an allergic reaction in the eye, the child may have conjunctival congestion, accompanied by itchy eyes and other discomforts. It is recommended that patients with obvious eye congestion should consult the hospital in a timely manner to assess their condition and follow the doctor’s instructions for treatment.