Psyllium is a form of fiber made from the husks of the Plantago ovata plant's seeds. It sometimes goes by the name ispaghula. It's most commonly known as a laxative.

It increases the bulk in your stool, an effect that helps to cause movement of the intestines. It also works by increasing the amount of water in the stool, making the stool softer and easier to pass. Psyllium, one type of bulk-forming laxative, has also been used along with a proper diet to treat high cholesterol.