Coronary groove is a little swollen without pain and itching causes include allergy, glans, genital herpes, penile cancer and so on. 1. Allergy: in case of allergy, at this time, due to the allergic reaction, it can lead to the phenomenon of redness and swelling of the coronary groove. 2. glansitis: in case of glansitis, at this time, due to bacteria and other infections of the glans, triggering inflammation of the glans, redness and swelling can also occur. 3. genital herpes: when the patient is infected by herpes viruses, these viruses will trigger the damage of the coronal sulcus, resulting in its redness and swelling. 4. Penile cancer: when the tumor cells proliferate a lot, the swelling of the coronary groove will also appear. There may be other reasons for a little swollen coronary groove without pain or itching, and patients need to consult the doctor in time for examination and early treatment.