Psyllium , or ispaghula , is the common name used for several members of the plant genus Plantago whose seeds are used commercially for the production of mucilage. Psyllium is mainly used as a dietary fiber to relieve symptoms of both constipation and mild diarrhea, and occasionally as a food thickener. Allergy to psyllium is common in workers frequently exposed to the substance.

Use of psyllium in the diet for three weeks or longer may lower blood cholesterol levels in people with elevated cholesterol, and may lower blood glucose levels in people with type 2 diabetes. Use of psyllium for a month or longer may produce a small reduction in systolic blood pressure.

The plants from which the seeds are extracted tolerate dry and cool climates, and are mainly cultivated in northern India.