Can Ground Flaxseed Cause Bowel Obstruction?

Flaxseed is a dietary supplement often used for its laxative properties. Ground flaxseeds contain soluble fiber that may improve bowel regularity. However, when taken in excess ground flaxseeds can cause constipation. In some cases, constipation is severe enough to obstruct the intestines or bowels. Flaxseed must be taken with care to avoid this uncomfortable side effect.

Ground flaxseeds next to a wooden scoop with whole flaxseed. (Image: Magone/iStock/Getty Images)

What is Flaxseed?

Flaxseeds are tiny, dark seeds that are around the size of a sesame seed. You can often find them whole in multigrain breads or in certain cereals. Flaxseeds can be purchased whole or ground, and are also available as over-the-counter dietary supplements. Because you can purchase them without a prescription, flaxseeds are a popular natural source of dietary fiber. According to Medline Plus, this is their most common reported use. However, like any supplement ground flaxseeds can cause unpleasant side effects, including severe constipation.

Bowel Obstructions

Constipation occurs when stool is too compacted or firm to pass easily through the bowels and out of the body. When constipation is severe, the stool may stop moving altogether and a blockage can occur. Medline Plus reports that ground flaxseeds increase bulk in the stool, which ordinarily improves the regularity of bowel movements. However, if taken in excess they can cause enough bulk to obstruct the bowels altogether. Ground flaxseeds can also cause a condition called ileus, which is a blockage higher up, in the intestines. According to the National Center for Complementary and Alternative Medicine, bowel and intestinal obstructions caused by any type of flax supplements are rare. Drinking plenty of water and not exceeding your daily recommended dose can help.

Who is at Risk?

While the risks are slim, some people who are at a higher risk for bowel obstructions should avoid fiber-rich flaxseed supplements. Those who already have an ileus or bowel obstruction should not use ground flaxseed unless recommended to do so by their physician. In addition, some people have naturally narrow intestines, leaving them more prone to bowel obstructions than the average person. These individuals should also avoid most flaxseed supplements. Natural Standard reports that flax oil is still generally safe for these populations, and offers omega-3 benefits without compromising intestinal or bowel function.


Most people can take flaxseed safely by following a few precautions. First, always check with your doctor before using any supplement, including flaxseed. It can interact with certain medications, including blood pressure and certain psychiatric drugs. Next, do not exceed the recommended daily dose. While your doctor can provide more specific guidelines, National Standard reports most dosages range from 10 to 250 mg per day. Finally, drink plenty of water and monitor your bowel movements. If you become more bloated, experience increase abdominal cramping or pain when trying to pass stool, stop taking the supplement and check in with your doctor.

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