Red marks on male glans may be erythema, and the appearance of erythema may be related to glansitis, erythema proliferatum, allergy and so on. 1. glans inflammation: due to trichomonas, mycoplasma and other pathogenic bacteria infection, causing local inflammation, the glans appear papules or erythema, gradually expanding, clear edge, erythema can be seen on the pinhead size of small blisters, and finally formed erosion surface. 2. Erythema proliferatum: mainly thought to be related to congenital factors, self-factors and viral factors. The long foreskin is easy to be stimulated by the foreskin scale and so on. The appearance of erythema is slightly elevated, with clear boundaries and a velvety appearance on the surface. 3. Allergy: it may be in contact with condoms or other substances, causing local allergic reactions, appearing local sudden redness, irregular light red spots, often accompanied by slight edema. When men have red spots on the glans, they should consult a doctor in time, follow the doctor’s instructions for further examination, clarify the cause with the help of the doctor, and carry out targeted treatment or therapy.