(psyllium husk) The husk of the dried ripe seeds of the Plantago psyllium, P. Indica, P. Ovata, and P. Arenaria plants with laxative and cholesterol lowering activities. The husks contain mucilage that swells on exposure to water and provides an indigestible mucilaginous mass in the intestines, thereby causing lubrication, contraction of the smooth muscles of the intestinal walls, and thus stimulating bowel movement. Psyllium husk is rich in soluble fiber and has a cholesterol-lowering effect.

A plant with seeds that are used as a mild laxative. The outer layer of the seeds swells when wet. This increases the size of stool and helps it pass more easily through the intestines (lower part of the digestive tract). Psyllium is a type of bulk laxative.