Cytokine Toxicity and Bacterial Dysbiosis in Chemotherapy- and/or Radiotherapy-Induced Oral Mucositis: Pathophysiological Mechanisms and Therapeutic Interventions

Chemotherapy- and/or radiotherapy-induced oral mucositis (CRIOM) is a common complication in patients with head and neck cancer, driven largely by excessive proinflammatory cytokine signalling and treatment-associated bacterial dysbiosis. This narrative review synthesizes current mechanistic evidence and summarizes emerging therapeutic strategies targeting these pathways. Research indicates that elevated levels of IL-1β, IL-6, TNF, iNOS, and nitric oxide amplify tissue injury and ulceration, while disruption of oral and gut microbial communities, characterized by loss of beneficial commensals and enrichment of pathogenic taxa, further exacerbates mucosal inflammation. Anti-inflammatory agents, including pentoxifylline, atorvastatin, trans-caryophyllene, azilsartan, recombinant human IL-11, and low-level laser therapy have been shown in preclinical models to reduce cytokine levels and promote mucosal healing. Similarly, microbiome-targeted approaches, such as oral microbiota transplantation and multi-strain probiotic formulations, have demonstrated potential in restoring microbial balance and attenuating CRIOM severity, with current evidence including both preclinical and clinical studies. Overall, current findings highlight cytokine toxicity and dysbiosis as synergistic drivers of CRIOM and support anti-inflammatory and microbiome-modulating strategies as promising adjunctive approaches; however, further well-designed clinical studies are required to validate their efficacy and guide clinical translation.