Mucositis is a common complication of cancer therapy and can be a debilitating and dose-limiting toxicity. Nearly all patients with head and neck cancer treated with radiotherapy develop some degree of mucositis, as do the majority of patients undergoing high-dose chemotherapy in conjunction with hematopoietic stem cell transplantation. Mucositis can have significant clinical and economic consequences. It is associated with severe pain that requires opioid analgesics and often results in the loss of critical functions such as speech and swallowing. Swallowing difficulties can lead to dehydration, weight loss, and the need for nutritional support. Furthermore, patients with mucositis are at increased risk of infection. Unscheduled dose reductions or treatment breaks due to severe mucositis may potentially compromise the efficacy of therapy and result in diminished quality of life. Treatment costs for patients with mucositis are substantially higher due to increased rates of hospitalization, opioid use, and a greater need for fluids and nutritional support. Costs generally increase as a function of mucositis severity. Effective treatments to prevent or reduce the incidence and severity of mucositis are needed to decrease function loss, minimize symptom burden, and lower treatment costs.