The use of high-dose baclofen emerged in 2008 in the treatment of alcohol-use disorders. Its prescription is still off-label in France, but recent trials have suggested the interest of using high doses for alcohol dependence, so we have to deal with an increase in its use. However, we still have few data about the adverse effects of a high-dose baclofen prescription, especially in complex addictive disorders. We present a case of a 32-year-old man who sought treatment for gambling disorders (GDs). He had complex addictive disorders, including alcohol-use disorders and GDs. He developed a severe GD, after treatment with a high dose of baclofen. The maximum dose was 160 mg/day, prescribed for his alcohol-use disorders. According to the Naranjo algorithm, the score was +7, it enabled to conclude that problem of gambling was probably imputable to baclofen. We discuss this case with reference to literature.