Ritalin (methylphenidate) is manufactured by CIBA-Geigy Corporation, and is supplied in 5 mg., 10 mg., and 20 mg. tablets, and in a sustained release form, Ritalin SR as 20 mg. tablets. It is water soluble and is intended for oral use. Many non-medical users, however, crush the tablets and either snort the resulting powder, or dissolve it in water and "cook" it for intravenous injection. It is a Schedule II Controlled Substance under both the federal Controlled Substances Acts.

A growing number of youngsters taking the drug Ritalin® (methylphenidate) experience overdose, researchers report. The study looked at the frequency of Ritalin overdose cases reported to a regional poison control center in Detroit. Children ages 6 to 9 years were at the greatest risk of overdose, compared with other age groups. Over a two-year period, 289 cases were reported. Of these, 31% developed symptoms. Most common adverse effects included tachycardia, agitation and lethargy. Most cases were due to parents or caregivers unintentionally giving patients excessive amounts of the drug.

Signs and symptoms of an acute overdose of Ritalin include:

• vomiting
• agitation
• tremors
• hyperreflexia
• muscle twitching
• convulsions (may be followed by coma)
• confusion
• hallucinations
• delirium
• sweating
• flushing
• headache
• hyperpyrexia
• tachycardia
• palpitations
• cardiac arrhythmias
• hypertension
• mydriasis
• dryness of mucous membranes
• exaggerated feeling of elation
• enlarging of the pupil of the eye
• extremely elevated body temperature
• high blood pressure