Buy Ritalin online should be taken 30 to 40 minutes before having a meal. It is to be taken twice or thrice a day. It is better to take the first dose of Ritalin early in the morning. If taken later in the day, it might cause insomnia. The dosage varies from patient to patient, consult your doctor before starting Ritalin. For children, the initial dose should be 5mg twice a day every day. The dosage can be increased from 5 to 10 mg on a weekly basis. For adults, the daily dose varies from 20 to 30 mg twice a day. The dose should not exceed 60 mg in a day. If you do not see any betterment in your condition even after using Ritalin then contact your doctor immediately.