Hyperthyroidism (Overactive Thyroid) and IBS

The Effects of Hyperthyroidism on Your Digestive System

Prescription for thyroid testing
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There is no direct relationship between hyperthyroidism, commonly referred to as overactive thyroid, and irritable bowel syndrome (IBS). However, it is possible for a person to have both conditions at the same time. This article provides a brief overview of hyperthyroidism and discusses its effect on your digestive system, so that you have a deeper understanding as to how your thyroid disease may be affecting your IBS symptoms.

What Is Hyperthyroidism?

Hyperthyroidism is a condition in which the thyroid produces more of its hormones than the cells of the body need to function. This excess results in a "speeding up" of many of the body's systems. The most common cause of hyperthyroidism is Graves' disease. Less common causes of hyperthyroidism include thyroid nodules, inflammation of the thyroid, Hashimoto's disease, eating excessive amounts of iodine, and being overmedicated for hypothyroidism.

Effect of Hyperthyroidism on Digestion

The symptoms of hyperthyroidism are quite varied as it is a condition that affects the entire body. So as to best understand how your thyroid disease may be affecting your IBS, we will limit our discussion here to the digestive effects of hyperthyroidism. The following symptoms are thought to be the result of increased motility as a result of hyperthyroidism. When no other digestive illnesses are present, these symptoms should go away when thyroid levels are stabilized.

It is estimated that as high as one out of every four patients with hyperthyroidism reports problems with diarrhea. There are several possible reasons for this. One may simply be the speeding up of the process of digestion. It is also possible that the thyroid disease affects the cells in the lining of the intestines, causing them to secrete excessive fluid.

Last, the increased appetite resulting from the condition may result in an increased intake of fat into the diet. Fat in the diet may serve to further increase the speed of intestinal contractions. A side effect of this rapid transit time is that the fat that is ingested has less time to mix with digestive enzymes. This reduces the absorption of fat by the body and increases the fat level of stools.

Increased Risk of Digestive Diseases

As stated above, there is no evidence of increased risk of developing IBS when you suffer from hyperthyroidism. However, having hypothyroidism raises your risk of two other digestive diseases, both with symptoms that are similar to IBS:

What to Do If You Have IBS and Hypothyroidism

  1. The most important thing to do if you have both health conditions is to make sure that your thyroid disease is being treated properly. This will ensure that your thyroid is not playing any part in your digestive symptoms.
  2. Make sure that before your doctor ruled out either celiac disease or ulcerative colitis before they gave you a diagnosis of IBS.
  3. Digestive health requires an adequate intake of dietary fiber. If you need to increase the fiber in your diet, do it slowly to allow your body time to adjust without aggravating your IBS symptoms or throwing off your body's ability to absorb your thyroid medication.
  1. Reduce the level of fat in your diet, as meals high in fat can speed up the motility of your colon, resulting in cramps and diarrhea.


Daher, R., et.al. "Consequences of dysthyroidism on the digestive tract and viscera" World Journal of Gastroenterology 2009 15:2834-2838.

Ebert, E. "The Thyroid and the Gut" Journal of Clinical Gastroenterology 2010 44:6 402-406.

Hyperthyroidism. National Institute of Diabetes and Digestive and Kidney Diseases.. https://www.niddk.nih.gov/health-information/endocrine-diseases/hyperthyroidism.