Purpose To update the clinical practice guidelines for the use of antimicrobials, mucosal coating agents, anesthetics, and analgesics for the prevention and/or treatment of oral mucositis (OM). Methods A systematic review was conducted by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). The body of evidence for each intervention, in each cancer treatment setting, was assigned an evidence level. The findings were added to the database used to develop the 2014 MASCC/ISOO clinical practice guidelines. Based on the evidence level, the following guidelines were determined: Recommendation, Suggestion, and No Guideline Possible. Results A total of 9 new papers were identified within the scope of this section, adding to the 62 papers reviewed in this section previously. A new Suggestion was made for topical 0.2% morphine for the treatment of OM-associated pain in head and neck (H&N) cancer patients treated with RT-CT (modification of previous guideline). A previous Recommendation against the use of sucralfate-combined systemic and topical formulation in the prevention of OM in solid cancer treatment with CT was changed from Recommendation Against to No Guideline Possible. Suggestion for doxepin and fentanyl for the treatment of mucositis-associated pain in H&N cancer patients was changed to No Guideline Possible. Conclusions Of the agents studied for the management of OM in this paper, the evidence supports a Suggestion in favor of topical morphine 0.2% in H&N cancer patients treated with RT-CT for the treatment of OM-associated pain.