However, individuals vary. Start with only one drink several hours post dosage and see what your reactions are. I wouldn't go past two. There have been no studies in animals or humans concerning this drug. There are no anecdotal studies in the literature concerning case studies.
Risks are unknown currently.
Several cases of Tourette's Syndrome have been reported as well, but is a rare problem. Ritalin use in children is based on effectiveness. That is, using the minimal dose to decrease the hyperactivity. Very large doses are occasionally used, focusing on the effect. Once the child is normal the dosage is slowly decreased until the child becomes more active.