Digestive Health Irritable Bowel Syndrome Related Conditions Is There a Link Between IBS and Thyroid Disease? By Barbara Bolen, PhD Updated on October 27, 2022 Medically reviewed by Shadi Hamdeh, MD Print If you have thyroid disease as well as irritable bowel syndrome (IBS), it's understandable to wonder if there's a connection between the two. Although there are numerous health problems that IBS patients experience at a higher rate than others, there's no evidence that having thyroid disease causes IBS or vice versa. That said, thyroid disease can cause similar gastrointestinal symptoms to those of IBS, so it can be easy to conflate them. Verywell / Michela Buttignol Digestive Symptoms in Thyroid Disease Your thyroid gland is responsible for releasing hormones that affect the way cells work throughout your body. When the thyroid is not functioning properly, this release of hormones is either excessive, resulting in hyperthyroidism, or deficient, resulting in hypothyroidism. As these hormones are involved in metabolism and digestion, a problem with the thyroid can result in gastrointestinal (GI) symptoms. When hormone levels are high, as in Graves' disease (the most common form of hyperthyroidism), intestinal motility is increased and the lining of the intestine may secrete more fluids, resulting in symptoms such as: DiarrheaIndigestion (dyspepsia)Increased appetiteFat malabsorption What Is Chronic Diarrhea? With hypothyroidism, the action of the gut is slowed, leading to: ConstipationLess frequent bowel movementsAbdominal discomfort and bloating Constipation and Hypothyroidism IBS, Thyroid Disease, and SIBO Small intestinal bacterial overgrowth, known as SIBO, occurs when excessive amounts of gut bacteria accumulate in the small intestine and cause symptoms such as bloating, constipation, and diarrhea. Hypothyroidism and IBS are two of the conditions associated with SIBO, as both can result in decreased intestinal motility. This essentially causes the bacteria to "back up" instead of being released during the normal digestive process. While the relationship between IBS and SIBO is not clear—and is, in fact, controversial—a 2014 review of the literature concluded that SIBO may be present in as many as 50 percent of people with hypothyroidism. Patients with chronic GI symptoms in hypothyroidism should be evaluated for the possibility of SIBO. Treatment with antibiotics has been found to be effective in managing the condition. The SIBO Theory for IBS A Word From Verywell Because GI symptoms in IBS and thyroid disease often overlap, it can be tricky to determine the underlying cause. As part of the routine diagnostic workup for IBS, it's essential that your healthcare provider rule out the presence of thyroid abnormalities; this can be done via a simple blood test. Getting proper treatment for thyroid disease should help relieve your related digestive symptoms, but it will not relieve symptoms caused by IBS. Make sure to work with your healthcare providers to get to the bottom of which condition is causing which symptoms so you can get an appropriate diagnosis and effective treatment. 4 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. National Institute of Diabetes and Digestive and Kidney Diseases. Graves' Disease. National Institute of Diabetes and Digestive and Kidney Diseases. Hypothyroidism (Underactive Thyroid). Patil AD. Link between hypothyroidism and small intestinal bacterial overgrowth. Indian J Endocrinol Metab. 2014;18(3):307-9. doi:10.4103/2230-8210.131155 Wilkins T, Pepitone C, Alex B, Schade RR. Diagnosis and management of IBS in adults. Am Fam Physician. 2012;86(5):419-26. Additional Reading Ebert E. The thyroid and the gut. Journal of Clinical Gastroenterology. 2010 44:6 402-406. doi:10.1097/MCG.0b013e3181d6bc3e National Institute of Diabetes and Digestive and Kidney Diseases. Hyperthyroidism (Overactive Thyroid). https://www.niddk.nih.gov/health-information/endocrine-diseases/hyperthyroidism National Institute of Diabetes and Digestive and Kidney Diseases. Hypothyroidism (Underactive Thyroid). https://www.niddk.nih.gov/health-information/endocrine-diseases/hypothyroidism Patil, A. Link between hypothyroidism and small intestinal bacterial overgrowth. Indian J Endocrinol Metab. 2014 May-Jun; 18(3): 307–309. doi: 10.4103/2230-8210.131155 By Barbara Bolen, PhD Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit