Attention-deficit hyperactivity disorder (ADHD) is characterized by inattention, hyperactivity, impulsiveness and problems in other higher cognitive processes such as executive function deficits. Currently, there are many treatment modalities, of which pharmacotherapy is the most strongly supported by scientific and clinical evidence. Stimulants, which are first choice in the pharmacological treatment of ADHD, block dopamine reuptake by binding the dopamine transporter and so increasing the concentration of dopamine in synaptic clefts. Stimulants are effective in improving core ADHD symptoms, as well as the nonspecific symptoms, such as aggressiveness and oppositional behavior. Frequently reported short-term adverse effects are decreased appetite, sleep disturbance, headache, dizziness and irritability. Although questions have been raised about the long-term side effects of stimulants, including growth suppression, cardiovascular events, and abuse potential, there is no clear evidence to support these concerns.