Oxytocin, due to its potential for modulation of cravings, is a possible alternative therapy for alcohol dependency. Management or cessation of alcohol use can increase the survival rates in cancers affected by alcohol abuse. The present study is an experimental single-case, reversal design study that has a multiple baselines and a 6- month follow-up. The study was conducted between January 2014 and November 2015. The patient was a 67-year-old man, known to abuse alcohol, who had a diagnosis of metastatic oropharyngeal squamous cell carcinoma and dysthymia syndrome. He was selected by a respondent-driven sampling method. The patient was treated with intranasal oxytocin in two stages and for six weeks. In the control phase, he used a placebo. The primary outcomes were the Addiction Severity Index results and changes to the Difficulties in Emotion Regulation Scale. The secondary outcome was the relationship between emotion regulation and addiction severity. The data were analyzed by the generalized estimation equation, linear mixed models (random effect model) with repeated measures, and correlation with repeated measures. Primary outcomes showed that intranasal oxytocin caused a significant decrease in addiction severity in its interaction with regulation of emotion. However, this reduction was not sustained until the follow-up stage. Secondary outcomes showed a direct relationship between the difficulty in controlling emotions and the severity of alcohol addiction. Oxytocin could decrease addiction severity by decreasing cue reactivity; thus, it could be considered an effective intervention in the field of addiction.