What causes acne on the back?

Back acne—commonly referred to as “bacne”—is a frequent dermatologic concern that shares the same underlying pathophysiology as facial acne vulgaris. It arises from a combination of factors including excessive sebum production, follicular hyperkeratinization (abnormal shedding of skin cells within hair follicles), colonization by *Cutibacterium acnes* (formerly *Propionibacterium acnes*), and subsequent inflammation. The back is particularly prone due to its high density of sebaceous glands and thicker stratum corneum, which can impede normal desquamation.

Contributing or exacerbating factors include occlusion from tight-fitting clothing, backpacks, or sports equipment; friction or sweating during physical activity; use of heavy or comedogenic skincare or hair products (e.g., oily conditioners or sunscreens that migrate down the back); hormonal fluctuations (especially androgen-driven increases in sebum, common in adolescence, polycystic ovary syndrome, or adrenal disorders); and genetic predisposition. Stress may also play a role via neuroendocrine modulation of sebaceous gland activity.

Less commonly, persistent or atypical back lesions may reflect other conditions such as fungal folliculitis (*Malassezia* spp.), pityrosporum folliculitis, keratosis pilaris, hidradenitis suppurativa, or drug-induced acneiform eruptions (e.g., from corticosteroids, lithium, or certain biologics). A thorough clinical evaluation—including lesion morphology, distribution, duration, and associated symptoms—is essential to distinguish these entities and guide appropriate management.

Treatment typically begins with topical agents such as benzoyl peroxide, salicylic acid, or retinoids, often combined with gentle cleansing and non-comedogenic moisturizers. For moderate-to-severe cases, oral antibiotics (e.g., doxycycline or minocycline), hormonal therapy (e.g., combined oral contraceptives or spironolactone in eligible individuals), or systemic isotretinoin may be indicated. Lifestyle modifications—including regular laundering of bedding and athletic wear, avoiding prolonged sweat retention, and minimizing occlusive products—are integral to long-term control.