Enlarged penis in small children may be caused by trauma, infectious factors, and allergies. 1. trauma: for example, the penile area was hit by external force, resulting in damage to the penis, will cause penile enlargement, accompanied by redness, subcutaneous bruising and pain and other symptoms. 2. Infection factors: children do not pay attention to the lower body hygiene, and the presence of circumcision, may be induced by the foreskin glans, the infection continues to worsen, will lead to penis enlargement, accompanied by penis itching, tingling and other symptoms. 3. Allergic factors: for example, allergy to toiletries, so that the penis part of the allergic reaction is more serious, will lead to penile enlargement, accompanied by intense itching and redness. There are many reasons why children have enlarged penises, so parents are advised to take their children to the doctor for examination and treatment in time to avoid adverse effects.