Red spots on the penis may be related to genital herpes, syphilis, glansitis and other diseases. 1. genital herpes: caused by the herpes zoster virus infection, preferably in the anus and the skin around the genitals, the typical symptom is the appearance of local skin blisters, blisters have obvious burning sensation, pain, and itching, once the blisters rupture, vesicles may form, and then scabs will be formed. 2. syphilis: small erythema appears on the glans, penis, prepuce tie and other parts of the glans, after which the erythema will be necrotic and form small ulcers. 3. glansitis: the onset of the disease is mainly associated with various pathogenic infections, or with external stimuli, autoimmune and other factors, manifested in the glans penis skin red spots, edema or erythema, which may be accompanied by itching and pain, and in severe cases, may form erosion or ulcers. There are many other reasons that can lead to red spots on the penis, it is recommended to go to a regular hospital in time to do a systematic examination to identify the cause of the disease, and actively treat or deal with it, so as not to delay the condition.