Studies on humans indicate that Ritalin may increase the effect of some drugs. Caution should be used in prescribing Ritalin to patients with a history of drug dependence or alcohol, or emotionally unstable patients. These patients may increase the dosage on their own. Long term abuse of Ritalin can lead to increased tolerance and psychic dependence with a range of abnormal behavior. Psychotic behavior can occur.
Drug withdrawal requires careful supervision.
Severe depression can occur during the withdrawal process and the effects of the previous over activity can be unmasked. The personality problems that lead to the abuse will require long term follow-up. The most common side effects are insomnia and nervousness. The most common side effects in children include abdominal pain, insomnia, loss of appetite, rapid heartbeat, and weight loss during long term therapy. Rare reports of Tourette's syndrome exist.