Red penis head in men may be caused by circumcision and glansitis, allergy and other reasons. 1. Circumcision glansitis: usually the foreskin is too long and not clean enough, which can lead to reddening, swelling and itching of the penis head. If left untreated, erosion, ulcers, and even purulent discharge can also occur. 2. Allergy: For example, if men use irritating toiletries or are allergic to newly purchased underwear, resulting in an allergic reaction in the penile area, it can cause redness in the head of the penis, which can also be accompanied by itching and other symptoms. Redness of the head of the penis in men may also be related to other causes, when male patients have symptoms of redness of the head of the penis, they should go to the hospital in a timely manner, under the guidance of the doctor to clarify the cause and treatment.