Anorectal care products cause variable inflammation and adverse barrier effects in a mucosal epithelial model

Introduction: Sexually transmitted infections (STIs) and colorectal cancer (CRC) are rising in the United States, yet their shared mucosal environment remains underexplored. Rectal douching, a common practice among individuals engaging in receptive anal intercourse, has been epidemiologically linked to increased STI and HPV risk, but biological mechanisms are unclear. Methods: Using a human colorectal epithelial co-culture model (Caco-2/HT29-MTX-E12), we compared the effects of common douching products on cell viability, barrier integrity, and cytokine response. Results: Hyperosmolar or surfactant-containing solutions, including saline enemas, detergents, and soaps, caused rapid declines in metabolic activity and transepithelial electrical resistance, coupled with IL-6 and TNF-α upregulation. In contrast, isotonic formulations maintained epithelial viability and barrier function comparable to buffered controls while reducing inflammatory signaling. Discussion: These findings provide mechanistic evidence that many consumer douching products compromise mucosal health and highlight the feasibility of harm-reduction designs for safer anal hygiene and sexual preparation.