Psyllium seed is used mainly for its laxative properties. Due to the swelling of its husk in water, a viscous solution is formed that keeps feces hydrated and soft. This bulking activity promotes the healthy movement of feces.
There are a few similar species of Psyllium existing around the world. Plantago psyllium, Plantago indica, and Plantago ovata Forsk. are the most frequently used. These annual plants are native to the Mediterranean region and the seeds and seed husks are used medicinally.
Psyllium is most often sold in bulk, although various solid bars have also become available. It is also is one of the most popular additions to bulking laxatives, and is often added to a cholesterol-reducing diet.
There have been some cases of allergic responses to psyllium, although these seem to be rare.
As with other water-retaining fibers, a choking hazard does exist if improper mixing or inadequate liquid intake allows the psyllium powder to remain in the throat as it begins to swell. General caution usually prevents this from happening.