Donna H.,   Thanks for your question.  Niacin and Niaspan are both forms of a B vitamin called nicotinic acid.  It has shown to improve levels of cholesterol and other forms of fat in the blood.  The difference between the two is that Niacin is a short acting form that must be taken in multiple doses through the day.  Niaspan, on the other hand, is a slow release tablet that is taken once a day.  They both can produce side effects that usually improve with time.  Since Niaspan is released slowly and continuously, it might have less side effects than Niacin.    Please review other areas of this website about cholesterol and ways to control it - medication as well as dietary.    Thank you.   Martin Cane, M.D.