Does Pure Psyllium Husk Interfere With Warfarin?

Commonly used as an over-the-counter laxative, psyllium is derived from the husk and seeds of the Plantago ovata herb 1. Psyllium use can, however, interfere with the proper function of several types of drugs, including blood thinners like Warfarin 1. Before using psyllium, talk to your doctor about any potential dangers and side effects 1.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


Pure psyllium husk is used as an oral bulk-forming laxative 1. After you take them, bulk-forming laxatives like psyllium swell with water and form a large, viscous mass that stimulates intestinal muscle contractions as it moves through the digestive tract 1. These contractions help soften the stool, making psyllium an effective treatment for constipation 1. Psyllium is used to help promote bowel regularity and, because of its capacity to absorb liquid, can also treat diarrhea 1. Research indicates that psyllium use may lower cholesterol levels and high blood pressure as well 1. Psyllium is sold commercially under a variety of brand names, including Metamucil, Fiberall, Reguloid and V-Lax 1.

Effect on Warfarin

Pros & Cons of Metamucil

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Warfarin -- also known by its brand name Coumadin -- is an anticoagulant or blood thinning medication that should not be taken with psyllium 1. Doctors advise that patients taking warfarin should avoid changing their eating habits in any way that could impact the amount of vitamin K they absorb. Because psyllium use can temporarily alter absorption in the digestive system, it may disrupt vitamin K levels and therefore change the effectiveness of warfarin 1. However, more research is needed to determine the extent of psyllium's effect on warfarin 1.

Other Interactions

Psyllium use may interfere with the function of medications other than warfarin 1. Other drugs like digoxin, nitrofurantoin or salicylates, such as aspirin, should be taken either 3 hours before or 3 hours after using psyllium 1. Consult your doctor before taking psyllium to make sure it doesn't cause an adverse reaction 1.


Psyllium Husk Allergy

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Psyllium may cause side effects such as bloating, headaches, itching and nausea 1. In rare instances, it may cause:

  • serious side effects like severe vomiting
  • abdominal pain
  • bleeding from the rectum
  • choking
  • a full body rash
  • extreme constipation

Avoid using psyllium if you have a history of intestinal blockages, high blood pressure, trouble swallowing, kidney disease, diabetes or heart disease 1. Psyllium can trigger allergic reactions in some people, so seek medical help immediately if you develop hives, have trouble breathing or experience swelling of the face or body 1.