Which of the following is a common side effect of stimulant medications used for ADHD?

Stimulant medications, commonly used to treat Attention-Deficit/Hyperactivity Disorder (ADHD), often lead to an increase in heart rate. This is because stimulants work by enhancing the activity of certain neurotransmitters in the brain, particularly dopamine and norepinephrine, which can lead to increased arousal and alertness. As these stimulants elevate the levels of these chemicals, they also stimulate the cardiovascular system, resulting in an elevated heart rate.

While some individuals might experience weight gain, increased anxiety, or excessive sleepiness as side effects, these are not typically associated as common with stimulant medications. In fact, weight loss is more frequently observed in users due to decreased appetite. Increased anxiety can occur in certain individuals but is not a universal side effect of stimulant medications. Likewise, excessive sleepiness is counterintuitive to the primary effect of stimulants, which is to promote wakefulness and concentration. Thus, the increase in heart rate distinctly stands out as a notable and expected physiological response to stimulant usage for ADHD.