Ritalin (Phenida) is also used the treatment of a sleep disorder called narcolepsy (an uncontrollable desire to sleep). Take Ritalin ( Phenida) exactly as prescribed by your doctor. Do not take in large or smaller amounts or for longer than recommended. Ad,omoster in divided doses 2 or 3 times daily, preferably 30 to 45 minutes before meals. Do not use Ritalin (Phenida) If you are allergic to methylphendate. the most adverse side effects are hives: difficulty breathing: swelling of your face, lips, tongue, or throat