Second, the man's glans is black or caused by long-term erection and congestion: long-term erection makes the glans in a state of congestion, leading to the glans being black. Such men need to arrange sexual intercourse reasonably and have a moderate sex life so as not to cause other male diseases.
Third, the foreskin balanitis may also cause the man's glans to turn black: it is mainly caused by inflammatory bacteria in the glans and long-term inflammatory stimulation.
Fourth, some drugs can also cause the glans penis to turn black.
The color of glans penis is pink or dark red, and the purple color of glans penis indicates poor blood flow and congestion. When patients with long foreskin are forced to have sex, because the foreskin is too narrow, they will shrink back and get stuck in the coronal groove of glans penis, which will hinder blood circulation, and the penis will turn purple and necrotic after a period of time.