Chemotherapy
Mucositis severity and duration in patients treated with CT depend on antineoplastic agents, treatment combinations, dosages and number of cycles:

• Lesions are seen mostly on the movable mucosae of the buccal mucosae and lateral and ventral surfaces of the tongue. The hard palate and gingiva appear not susceptible to CT-induced mucositis.
• The early clinical sign of mucositis is erythema, presenting about 4-5 days following CT infusion; 7 to 10 days after CT, ulcers develop, often requiring opioid intervention.
• CT-induced mucositis lasts approximately 1 week and generally heals spontaneously by 21 days after infusion.
• Neutropenia, caused by high dose CT, can predispose to bacteraemia, septicaemia and fungaemia, which may even be life-threatening.

Radiotherapy
Mucositis develop in nearly all patients receiving radiation therapy for heal and neck cancer and in most of patients undergoing total body irradiation therapy.
Mucositis severity and duration in patients treated with RT depend on radioactive source, cumulative dosage, dose intensity and volume of the irradiated mucosa:

• Inflammation appears at week 1-2 and can persists for 4-6 weeks.
• Most acute period at the end of RT (4 weeks' treatment).
• Nearly all patients will experience mucositis during RT (head and neck cancer).
• 88% of patients may experience grades III or IV mucositis with particularly aggressive therapies.
• Worse when chemoradiation is given (increasingly common).