Ritalin generally refers to methylphenidate hydrochloride extended-release tablets for the treatment of attention deficit hyperactivity disorder. Methylphenidate hydrochloride extended-release tablets are used to treat attention deficit hyperactivity disorder in children and adolescents with attention deficit hyperactivity disorder aged 6-17 years and adults with attention deficit hyperactivity disorder aged 18-65 years who meet DSM-IV diagnostic criteria. The effect lasts for 12 hours after administration and should be taken in the morning. Dosage may vary according to individual patient needs and efficacy. Adverse effects such as insomnia, dizziness, cough, vomiting, and fever may occur and should be noted after administration of this drug. This medication should not be taken by patients with significant symptoms of anxiety, nervousness, and agitation, as these symptoms may be exacerbated. Patients who are allergic to methylphenidate or other ingredients of this product and those with glaucoma should also not take this drug. Patients should use the drug under medical supervision.