Can i quit methylphenidate immediately or do i taper off slowly i am currently on 25mg in the am and 25 mg 4 5 hrs later it has not helped my add.?

Quitting: There should be no need to taper off of a stimulant that is short acting.

Depends: If you've been on mph for a long time you may wish to taper over 1-2 days to avoid fatigue & sleepiness. If you're switching to another medication, there is no need to taper. The way you're using mph may impact its effect. If its immediate release, waiting 4-5 hours between doses is too long & will lead to ineffectiveness. If you're swallowing it with an acidic beverage it may not be effective.

If you have a valid: Diagnosis of adhd-primarily inattentive type, don't give up after the first medication trial. Ther are 2 stimulants, each with many delivery systems. As dr. E. Said, it may be that the dose is too low or the dose are too far apart. Talk to your doctor about trying a long-acting methylphenidate (concerta or focalin) or amphetamine (vyvanse) that'll last ~12-14 hrs, respectively. See chadd.Org.