Psyllium, a bulk-forming laxative, is used to treat constipation. It absorbs liquid in the intestines, swells, and forms a bulky stool, which is easy to pass.
Psyllium comes as a powder, granules, capsule, liquid, and wafer to take by mouth. It usually is taken one to three times daily. Follow the directions on the package or on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take psyllium exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Summary from MedlinePlus.gov, click for more information.