Redness of the subcoronal sulcus is not necessarily syphilis, but may also be due to other etiologies such as circumcision and glans, external injuries, allergies, and so on. 1. Syphilis: in the early stage of the disease, it can lead to the appearance of erythema, pimples and other diseases in the affected area, and some patients may also have the symptom of redness in the coronal sulcus. 2. circumcision: it can lead to the patient’s glans, foreskin and the coronal groove and other parts of the redness, swelling, itching and other uncomfortable symptoms. 3. External injury: external injury to the coronary groove area can lead to redness and pain in the affected area. 4. Allergy: various sensitizing factors may lead to allergies in the glans and the coronal region, resulting in redness and itching in the coronal region. Coronary groin redness has more reasons, it is recommended that patients seek medical examination, diagnose the cause of the disease, and be targeted treatment.