What Causes Smegma?

In daily life, some men experience phimosis (excessively long foreskin). This condition requires timely treatment, as severe cases may significantly impair marital sexual function. What causes smegma?

What Causes Smegma?

Smegma is a secretion that accumulates within the preputial cavity and typically appears white or creamy-white. Historically, it was believed to originate from ectopic sebaceous glands located near the frenulum; however, histological studies have failed to identify such glands. Research has demonstrated that smegma is produced by tiny projections on the inner mucosal surface of the foreskin. Epithelial cells from this inner mucosa continuously proliferate toward the surface; upon reaching a certain stage, they undergo fatty degeneration, and the resulting degenerated tissue subsequently desquamates to form smegma.

When phimosis or true phimosis (tight, non-retractable foreskin) is present, smegma tends to accumulate within the preputial cavity. Its physiological role is to maintain moisture in the preputial cavity, thereby supporting normal penile sexual function. However, prolonged accumulation of smegma may predispose individuals to bacterial or fungal infections, leading to chronic irritation of the glans penis and potentially increasing the risk of penile cancer. Therefore, smegma should be cleaned regularly.

Smegma formation primarily results from phimosis—when the foreskin remains tightly covering the glans penis for extended periods, creating an environment conducive to smegma accumulation. Over time, this may lead to balanoposthitis (inflammation of both the glans and foreskin). To definitively eliminate smegma, circumcision is the first-line and definitive therapeutic approach. By surgically removing the redundant foreskin, circumcision effectively prevents smegma accumulation and reduces the risk of developing balanoposthitis.