[Methylphenidate and lisdexamfetamine toxicity in a patient with ADHD after gastric bypass].

The effects of gastric bypass on the efficacy of methylphenidate remain underexplored. Existing postoperative reports predominantly describe either unchanged or diminished efficacy, with only one prior case report documenting intoxication. We describe the case of a female patient exhibiting clinical signs of methylphenidate intoxication several weeks after a Roux-en-Y gastric bypass, followed by a similar reaction to a low dose of lisdexamfetamine. This is followed by a summary of postoperative changes reported in the literature regarding the effectiveness of methylphenidate and lisdexamfetamine, alongside an exploration of potential mechanisms for altered methylphenidate efficacy. As these changes remain incompletely understood, it is advised to closely monitor patients restarting methylphenidate or lisdexamfetamine post-gastric bypass for up to six months.