They might exhibit bizarre, repetitive behavior. Large doses can produce flushing, tremors and hallucinations. Death can be caused due to burst blood vessels, heart failure and fever. Violence is a leading cause of amphetamine-related deaths. Long-term effects for chronic heavy users are malnutrition and amphetamine psychosis, a mental illness.
Violent tendencies can develop after long regular use.
Ritalin is available in both short acting and sustained release doses. Short-acting Ritalin is available in 5 to 20 milligram tablets. In as little as 20 minutes it takes effect. This effect peaks in 45 minutes to an hour and is gone in 3 to 4 hours. The drug starts working in about 90 minutes.