Dexmethylphenidate, sold under the brand name Focalin among others, is a central nervous system (CNS) stimulant indicated in the treatment of attention deficit hyperactivity disorder (ADHD) in those over the age of five years.

[3] Serious side effects may include psychosis, sudden cardiac death, mania, anaphylaxis, seizures, and dangerously prolonged erection.

It is proposed that stimulants help ameliorate the symptoms of ADHD by making it easier for the user to concentrate, avoid distraction, and control behavior.

[13] The most common side effects associated with methylphenidate (in standard and extended-release formulations) are appetite loss, dry mouth, anxiety/nervousness, nausea, and insomnia.

Nervous system adverse effects may include akathisia (agitation/restlessness), irritability, dyskinesia (tics), lethargy (drowsiness/fatigue), and dizziness.

[16] Ophthalmologic adverse effects may include blurred vision caused by pupil dilatation and dry eyes, with less frequent reports of diplopia and mydriasis.

[19] Results from a 2024 systematic review showed that methylphenidate significantly improves ADHD symptoms and broadband measures but can cause appetite suppression and other adverse events in children and adolescents.

[30] A 2018 Cochrane review found that methylphenidate might be associated with serious side effects such as heart problems, psychosis, and death.

[31][a] The symptoms of a moderate acute overdose of methylphenidate primarily arise from central nervous system overstimulation; these symptoms include: vomiting, nausea, agitation, tremors, hyperreflexia, muscle twitching, euphoria, confusion, hallucinations, delirium, hyperthermia, sweating, flushing, headache, tachycardia, heart palpitations, cardiac arrhythmias, hypertension, mydriasis, and dryness of mucous membranes.

[32][33] A severe overdose may involve symptoms such as hyperpyrexia, sympathomimetic toxidrome, convulsions, paranoia, stereotypy (a repetitive movement disorder), rhabdomyolysis, coma, and circulatory collapse.

[34] Following injection of methylphenidate tablets into an artery, severe toxic reactions involving abscess formation and necrosis have been reported.

[35] Treatment of a methylphenidate overdose typically involves the administration of benzodiazepines, with antipsychotics, α-adrenoceptor agonists and propofol serving as second-line therapies.

[38] Methylphenidate has the potential to induce euphoria due to its pharmacodynamic effect (i.e., dopamine reuptake inhibition) in the brain's reward system.

Concomitant administration may require dose adjustments, possibly assisted by monitoring of plasma drug concentrations.