The goal of this clinical trial is to explore the effectiveness and adverse reactions of doxepin solution spray for alleviation of stubborn breakthrough pain induced by swallowing in patients receiving radiotherapy for nasopharyngeal carcinoma.
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Age ≥ 18 years.
Histologically confirmed as nasopharyngeal carcinoma, and currently undergoing radical radiotherapy or chemoradiotherapy.
Physical examination demonstrating the presence of radiation-induced mucositis in the oral cavity and/or oropharynx.
Known allergy to doxepin, tricyclic antidepressants, or any known component of the drug formulation.
Use of a tricyclic antidepressant or monoamine oxidase inhibitor within 14 days prior to registration.
Current untreated or unhealed oral candidiasis or oral herpes simplex virus infection.
Untreated narrow angle glaucoma within 6 weeks prior to registration.