Psyllium, also referred to as ispaghula, contains a high level of soluble dietary fiber, and is the chief ingredient in many commonly used bulk laxatives. Psyllium is well studied as a cholesterol lowering agent with generally modest reductions seen in blood levels of total cholesterol and low.....

Does it work?

Psyllium, also referred to as ispaghula, contains a high level of soluble dietary fibre, and is the chief ingredient in many commonly used bulk laxatives. Psyllium is well studied as a cholesterol lowering agent with generally modest reductions seen in blood levels of total cholesterol and low-density lipoprotein ("bad cholesterol"). Effects have been observed following eight weeks of regular use.

Dangers and possible side effects.....

Avoid if allergic or hypersensitive to psyllium, ispaghula, or English plantain (Plantago lanceolata). Avoid in patients with esophageal disorders, gastrointestinal atony, fecal impaction, gastrointestinal tract narrowing, swallowing difficulties, and previous bowel surgery. Prescription drugs should be taken one hour before or two hours after psyllium. Use cautiously with blood thinners, antidiabetic agents, carbamazepine, lithium, potassium-sparing diuretics, salicylates, tetracyclines, nitrofurantoin, calcium, iron, vitamin B12, other laxatives, tricyclic antidepressants, antigout agents, anti-inflammatory agents, hydrophilic agents, and chitosan. Use cautiously with diabetes and kidney dysfunction. Use cautiously if pregnant or breastfeeding.

References:

https://en.wikipedia.org/wiki/Psyllium_seed_husks