A little redness of the penis after sex may be caused by too much time for sex, or it may be caused by other reasons such as condyloma acuminatum, glansitis, and allergies. 1. Too much time for sex: If the time for sex is long, the penis will be rubbed for a long time, and the penis may be red after sex. This is a normal phenomenon, usually after reducing the frequency of sex, the symptoms will be relieved. 2. acromegaly: acromegaly is mainly due to human papilloma virus infection, the patient will be manifested in the penis glans surface reddish small particles, with the development of the disease will appear papillae, cauliflower-like pink superfluous organisms. So the patients appear warts, after sex will have penis a little red symptoms. 3. glansitis: glansitis is considered to be caused by bacterial, fungal and other pathogenic infections, or penile trauma, circumcision and other factors. Patients will have glans skin edema, erythema, pain and other manifestations, so that the patient will show a little red penis after sex. 4. Other: patients with a little red penis after sex may also be allergies, syphilis, gonorrhea and other diseases. Men after sex penis a little red to rule out physiological factors, the need for timely medical treatment, the patient should follow the doctor’s advice to choose the appropriate measures for treatment.