The strong edema on the left side of the foreskin may be caused by circumcision, foreskin inlay, allergy and other reasons. 1. Glans foreskin inflammation: If the patient has had circumcision, in the process of surgical operation, if the disinfection work is not done properly, so that the skin is infected by bacteria. This may lead to glans phimosis, redness, swelling and pain of the foreskin, and may even cause pus. 2. Foreskin embedded: If the patient’s foreskin is not reset in time after turning up, it may cause venous blood return obstruction. If the foreskin is turned over for a long time, it may lead to edema on the left side of the foreskin. 3. Allergy: If the left side of the foreskin of the patient accidentally came into contact with allergens or mosquito bites, condom allergy and so on. May also lead to the phenomenon of edema on the left side of the foreskin. If the patient appeared to the left side of the foreskin edema is very strong, it is recommended to consult a doctor in time, under the guidance of a professional doctor, to take the appropriate treatment plan.