Hallucinations during methylphenidate therapy

Patients:Three children, 7 year old adopted boy (Case 1), 12 year old boy (Case 2) and 7.5 year old boy (Case 3). 3 patients dropped out due to side effects. Follow-up was after > 2 years, 3 years and 2 years for Cases 1,2 and 3 respectively.; TypeofStudy:Three cases of children with attention deficit hyperactivity disorder (ADHD), who were treated with low doses of Ritalin and developed complex visual and haptic hallucinations. Case reports.; DosageDuration:Case 1: 0.3 mg/kg (7.5 mg) once daily. Duration was for 1 year. Case 2: 0.3 mg/kg (10 mg) once daily. Duration not stated. Case 3: 0.25 mg/kg daily (7.5 mg) once daily; Indications:3 patients with attention deficit hyperactivity disorder (ADHD). Coexisting diseases were oppositional defiant disorder (Case 1); cerebral palsy and low normal intelligence (Case 2); mild learning disabilities (Case 3).; Results:Case 1: the patient reported seeing and feeling snakes crawling on and around him starting 1 hour after drug ingestion. The teaching staff assumed an emotional problem and used psychological intervention to free him of these behaviors. When these proved ineffective and to rule out drug-induced hallucinations, placebo was substituted for Ritalin with immediate cessation of hallucinations. Pemoline was begun, and no psychiatric symptoms reappeared during a follow-up period of > 2 years. Case 2: Ritalin produced a marked improvement. One morning, the patient was observed crawling on the floor complaining that roaches were surrounding him. Ritalin was withdrawn, and there was no recurrence. However, deterioration in school performance was so dramatic that rechallenge with Ritalin was attempted. Immediate recurrence of hallucinations necessitated stopping Ritalin. Three-year follow-up evaluation has been uneventful. Case 3: treatment with Ritalin was successful. Several months later the patient became distressed, claiming that mosquitoes and other crawling creatures were in his bedroom and on him. After several days, Ritalin was stopped, the visual and haptic sensations ceased, and within a week he returned to sleep in his room. During a follow-up period of 2 years, there was no recurrence of the hallucinations.; AdverseEffects:3 patients developed visual and haptic hallucinations.; AuthorsConclusions:In summary, we describe three children with ADHD who manifested hallucinations as a side effect of Ritalin at low therapeutic doses These children were seen in our clinic during a 5-year period during which ≈ 2,000 children with ADHD were diagnosed and treated. The prevalence of hallucinations in conjunction with Ritalin is rare, probably < 0.2%. However, the comorbidities in our patients may have rendered them more vulnerable to hallucinationatory phenomena. Because Ritalin is a widely used, well-studied, and safe pharmacologic agent, physicians who prescribe Ritalin should be aware of even rare adverse manifestations occurring at therapeutic doses.; FreeText:Additional treatment: psychological intervention (Case 1).