Generally, the side effects of methylphenidate hydrochloride extended-release tablets include the following: first, causing cardiovascular symptoms in children. Taking methylphenidate hydrochloride extended-release tablets often causes symptoms such as panic, palpitations, rapid heartbeat, and even an increase in blood pressure in children. Secondly, it causes digestive tract symptoms. After taking the drug, it often causes poor appetite, vomiting, nausea, abdominal pain and other symptoms. In addition, it causes an increase in central excitability, which often leads to mental hyperactivity, restless sleep at night and even hallucinations.