Objective: Photobiomodulation therapy is recommended by multiple international societies for managing oral mucositis. These recommendations are based on extensive evidence. However, the search for an optimal photobiomodulation protocol continues. This mapping review focuses on a novel aspect of photobiomodulation therapy which is the immediate effect on pain levels associated with oral ulcerative conditions.
Data sources: This literature review systematically compiles and evaluates the evidence about oral mucositis, alongside other oral ulcerative conditions, as the protocols that achieved pain relief for these oral conditions may have potential applicability to oral mucositis management. The scientific database used was PubMed. 
Conclusion: Whereas most of the randomized controlled trials about photobiomodulation therapy for oral mucositis and other ulcerative oral diseases reported delayed pain relief, certain photobiomodulation therapy protocols reported immediate pain relief. The results of this review highlight the concept of preemptive photobiomodulation therapy, in which photobiomodulation therapy is delivered early in the development of oral mucositis throughout the oncotherapy and may achieve immediate pain relief consistently in most of the patients and close to a negligible pain level. Photobiomodulation therapy, as a powerful nonpharmacologic tool for immediate pain relief, has a great beneficial value in patients suffering from oral mucositis and other painful oral ulcerative diseases such as recurrent aphthous stomatitis and chronic graft-versus-host disease.