Methylphenidate (MPH) treatment 'may be associated with unacceptable side effects and risks' (J Clin Psychiatry, 1998; 59 [Suppl 7]: 42-9).
Physicians have received official warnings about the following adverse effects with Ritalin:
* nervousness and insomnia
* loss of appetite, anorexia, nausea and vomiting
* dizziness, palpitations, headaches
* elevated heart rate and blood pressure
* skin rashes and itching
* abdominal pain, weight loss, digestive problems
* toxic psychosis, psychotic episodes, drug-dependence syndrome
* severe depression upon withdrawal
* liver toxicity (especially carcinogenic).
Overdosing on MPH (more than 10 mg/day) may lead to agitation, hallucinations, psychoses, lethargy, seizures, tachycardia (rapid heartbeat), dysrhythmias, hypertension and hyperthermia (Curr Opin Pediatr, 2002; 14: 219-23). Severe social withdrawal, increased crying and irritability have also been reported after MPH treatment, as have 'explosive outbursts' (J Am Acad Child Adolesc Psychiatry, 2001; 40: 18-9).
Between 1990 and 2000, the US Food and Drug Administration's Division of Pharmacovigilance and Epidemiology collated 186 deaths and 569 hospitalisations due to MPH, mainly because of 'central or peripheral nervous system occurrences'.
In the US, Ritalin is a Schedule II Controlled Substance, which puts it in the same category as cocaine, heroin and methamphetamine. It is the fastest-growing illicit drug, and is either snorted like cocaine or injected like heroin. Such illicit use has caused several deaths among high-school children.