Hypothyroidism and Constipation

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Constipation is a common gastrointestinal concern that all of us experience at one point or another.

While many people think constipation is not a big deal, it never occurs without reason. Constipation is almost always a sign of some underlying health problem which only intensifies the importance of taking it seriously.

In this post, we focus on constipation and its potential association with hypothyroidism.

Keep reading to learn more about this subject.

Causes of constipation

Constipation doesn’t mean the same thing to all people.

For some people constipation refers to hard stools, straining (difficulty passing stools) and incomplete emptying after a bowel moment. For others, the term constipation means infrequent passage of feces or stool.

So, what is the accurate definition of constipation? It would be pointless to discuss its relationship with hypothyroidism without knowing what it, actually, is.

Constipation is defined as bowel movements that are difficult to pass and infrequent.

In fact, a person is considered constipated if he or she has three or fewer bowel movements a week. Constipation can be occasional (goes away quickly) or chronic (persistent). Chronic constipation refers to difficulty passing or absence of stool lasting for several weeks.

Unlike occasional constipation that is awkward, but not a huge threat to one’s health, the chronic type has a major impact on a patient’s quality of life.

The reason we have constipation is that stool or waste moves too slowly through the digestive tract.

In addition, this problem occurs when the stool can’t be successfully expelled from the rectum. Different causes may contribute to chronic constipation, such as rectal cancer, anal fissure, bowel obstruction, bowel stricture (narrowing of the colon), colon cancer, and others[i].

Other causes include problems with nerves around colon and rectum and conditions that affect hormones such as diabetes, hyperthyroidism, pregnancy, and hypothyroidism.

Constipation is a symptom of hypothyroidism

Hypothyroidism, or an underactive thyroid, is a defined as a disorder of the endocrine system wherein the butterfly-shaped gland doesn’t produce a sufficient amount of thyroid hormone for proper function.

Hypothyroidism occurs due to a number of causes including treatment for hyperthyroidism, autoimmune disease, thyroid surgery, radiation therapy, and some medications.

Symptoms of hypothyroidism vary and they depend on the severity of your condition. Many people don’t even know they are hypothyroid because symptoms develop over the years, they don’t pop up unexpectedly. Plus, signs of hypothyroidism are similar to those of other conditions thus making it more difficult for people to understand what’s going on.

One of the most common symptoms (and the least discussed) of hypothyroidism is constipation. Others include weight gain, fatigue, low libido, abnormal menstrual cycle, memory loss, depression, hair loss, dry and pale skin, dry hair, cold intolerance, muscle cramps, and irritability[ii].

Constipation being a symptom of hypothyroidism isn’t the only link between two conditions. Let’s inspect this relationship more thoroughly.

Constipation and hypothyroidism in children

Despite the fact that constipation is a common concern, most people feel uncomfortable talking about it. That’s why we don’t see many articles and hypothyroidism-related blogs discussing this subject. However, in order to manage your condition properly, it is important to address even those things that one may find embarrassing.

The relationship between constipation and hypothyroidism is not explored as well as it should be. Bennett W.E. et al explored the prevalence of hypothyroidism among children with constipation and found that only a small portion of children with this gastrointestinal concern had problems with the underactive thyroid gland.

That means that hypothyroidism is an unlikely cause of constipation in hypothyroid children. That being said, it is recommended that children with severe constipation undergo thyroid hormone evaluation[iii].

Goto S. et al explain that hypothyroidism may be associated with either severe constipation or megacolon that mimics Hirschsprung’s disease, a condition that affects large intestine and impairs passing of the stool. Hirschsprung’s disease is present at birth i.e., and it is a congenital condition that occurs due to missing nerve cells in the baby’s colon.

However, the mechanisms underlying this relationship are not very clear, scientists report.

Using rats, they found that hypothyroidism significantly impairs colonic motility and function[iv]. Colonic motility refers to bowel movements, and two primary types of impaired function are diarrhea and constipation.

Constipation and hypothyroidism in adults

While many studies have been conducted on hypothyroidism subject, many of them didn’t focus on constipation. In many cases, this was only one part of the whole research, but it doesn’t mean the evidence is weak. You’ll be surprised to know that a growing body of evidence confirms the link between constipation and hypothyroidism.

For example, The American Journal of Digestive Diseases published a study which explored intestinal disorders in hypothyroidism. The research found a severe functional deficiency of the small intestine and colon. Stimulation of small intestine showed a complete absence of motor response in patients with severe constipation.

Not only did the study confirm the existence of constipation in hypothyroid patients, but it also revealed that stimulation of small intestine could be a prognostic test which could show whether a patient would respond to hormonal therapy[v]. The inadequate intestinal function could dampen efficacy of the treatment.

In 2014, the Indian Journal of Endocrinology and Metabolism featured the study which reviewed current evidence on hypothyroidism, gastrointestinal (GI) motility and development of bacterial overgrowth in your small intestinal. The SIBO “small intestinal bacterial overgrowth” is a condition wherein the bacteria in your stomach overgrow and gets out of balance. The paper shows that hypothyroidism reduces the gastroesophageal motility and it is important for patients with indigestion to evaluate thyroid functions.

In healthy people, normal small gastrointestinal motility prevents overgrowth of bacteria, but more than half patients with hypothyroidism have SIBO. While diarrhea is rarely reported, constipation is a common concern in hypothyroid patients.

Gastrointestinal hypomotility in hypothyroid persons could promote overgrowth of bacteria thus causing chronic symptoms affecting digestive health and function. While many people associate SIBO with diarrhea, constipation is a common symptom too, especially in hypothyroid patients[vi].

A team of scientists from Turkey, whose findings were published in the Gastroenterology Research and Practice, also confirmed that hypothyroidism has a negative influence on GI motility. In addition, changes in the motor activity of digestive system could lead to constipation and gastric distension (bloating) in hypothyroid individuals.

Turkish scientists also confirm what we’ve already known – that a limited number of studies on this subject have been conducted. However, evidence shows hypothyroid patients have a major reduction in gastric emptying, but some studies found no relationship between deficiency in thyroid hormone, acid secretion, and gastric excretion.

On the other hand, further research found that depletion of thyroid hormones can, indeed, inhibit secretory functions of the digestive tract[vii], thus leading to constipation and other GI concerns.

Why does hypothyroidism cause constipation?

As seen throughout this post, current evidence confirms the relationship between constipation and hypothyroidism. You’re probably wondering why that happens in the first place. While exact mechanisms aren’t fully investigated, the culprit could be the fact that insufficient levels of thyroid hormones slow down the body’s functions.

Just like the above-mentioned studies revealed, hypothyroidism slows function of digestive tract thus causing irregular bowel movements or making it difficult for a person to eliminate waste from the body.

Moreover, digestive tract including both large and small intestine are lined with muscles. The proper function of these muscles is important for healthy digestion and bowel movements. In order to move waste or stool through the intestine to the rectum and out of the body, muscles need to contract.

Due to hypothyroidism contraction of muscles slows down and weakens. As a result, stool also moves slowly, and you experience infrequent bowel movements or difficulty passing stool.

Not only is constipation uncomfortable and frustrating, particularly when it’s chronic, but it can also decrease the efficacy of medications you’re taking. After all, therapy needs to be fully absorbed in order to work, but digestion-related problems like constipation impair absorption.

This only emphasizes the importance of management of constipation.

Things to avoid when constipated

Most people have constipation at some point in their life. Occasional constipation is one thing, it’s not that frustrating, but chronic or persistent constipation can have a negative impact on a patient’s quality of life especially if hypothyroidism is also involved.

While the uncomfortable problem, constipation can be managed successfully.

Effective management of constipation is all about learning what to do or things you should avoid. Below, you can take a look at some things to avoid doing when constipated[viii]:

  • Drinking caffeine and/or alcohol both caffeine and alcohol have dehydrating effects. Proper bowel movements require hydration but drinking too much coffee, or alcoholic beverages could only aggravate constipation
  • Eating too much processed food – these foods contain all sorts of ingredients that are used to enhance flavor but don’t deliver important nutrients. Your digestive system has enzymes to break down and absorb different types of food, but these enzymes don’t really work well with processed foods. Impaired digestion is the biggest risk factor for constipation
  • Too much dairy – they contribute to bloating, which makes it difficult for the body to pass the stool
  • Sedentary lifestyle – yet another factor that increases the risk of constipation or it aggravates your condition. Lack of physical activity decreases gut movement, weakens muscles, and decreases blood flow to digestive tract thus slowing down metabolism
  • Iron and calcium supplements while they are useful for prevention of deficiency and conditions that occur due to low levels of these minerals, iron and calcium supplements can slow down contractions in GI system
  • Excessive use of laxatives – although laxatives are an effective way to tackle constipation, the excessive use can make your body get used to laxatives, thus making it difficult to improve your digestion naturally
  • Other mistakes to avoid include adding too much fiber too fast, ignoring your body’s needs, skipping meals, just to name a few

Managing hypothyroidism-caused constipation

When you have hypothyroidism, it all comes down to proactive approach and management of symptoms you experience and constipation isn’t the exception from this rule. The first and most important step toward successful management of constipation is to treat hypothyroidism.

Chronic constipation is almost always a sign of some underlying health problem meaning that’s what you need to manage first in order to make this GI concern go away.

Sometimes this is easier said than done because hypothyroidism can be very tricky to control, but with doctor’s help and lifestyle modifications, you can do it.

Other things hypothyroid patients should do to manage constipation are[ix]:

  • Consult your doctor about medications and supplements you’re taking
  • Exercise regularly
  • Lower intake of processed foods
  • Stay hydrated throughout the day
  • Consider using laxatives, but don’t use them too much, this is yet another topic to discuss with your doctor
  • Manage stress
  • Don’t ignore, delay, or put off the urge for a bowel movement


Constipation is one of the most common gastrointestinal problems, and it can be either occasional or chronic.

Hypothyroidism can cause constipation due to hormone depletion that slows digestive functions and weakens muscle contractions. More studies are necessary to elucidate this subject entirely.


[i] Constipation, Mayo Clinic https://www.mayoclinic.org/diseases-conditions/constipation/symptoms-causes/syc-20354253

[ii] Hypothyroidism: overview, causes, and symptoms, EndocrineWeb https://www.endocrineweb.com/conditions/thyroid/hypothyroidism-too-little-thyroid-hormone

[iii] Bennett WE, Heuckeroth RO. Hypothyroidism is a rare cause of isolated constipation: 5-year review of all thyroid tests in a pediatric gastroenterology office. Journal of pediatric gastroenterology and nutrition. 2012;54(2):285-287. doi:10.1097/MPG.0b013e318239714f. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4985619/

[iv] Goto S, Billmire DF, Grosfeld JL. Hypothyroidism impairs colonic motility and function. An experimental study in the rat. European Journal of Pediatric Surgery 1992;2(1):16-21. Doi: 10.1055/s-2008-1063392 https://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-2008-1063392

[v] Duret RL, Bastenie PA. Intestinal disorders in hypothyroidism. The American Journal of Digestive Diseases 1971 Aug;16(8):723-7. https://link.springer.com/article/10.1007/BF02239597

[vi] Patil AD. Link between hypothyroidism and small intestinal bacterial overgrowth. Indian Journal of Endocrinology and Metabolism. 2014;18(3):307-309. doi:10.4103/2230-8210.131155. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4056127/

[vii] Yaylali O, Kirac S, Yilmaz M, et al. Does hypothyroidism affect gastrointestinal motility? Gastroenterology Research and Practice 2009 Dec. Doi: 10.1155/2009/529802 https://www.hindawi.com/journals/grp/2009/529802/

[viii] 7 things you should never do when you’re constipated. Women’s Health Mag https://www.womenshealthmag.com/health/a19950881/constipation-causes/

[ix] 8 tips to relieve hypothyroidism-related constipation, Everyday Health https://www.everydayhealth.com/hs/healthy-living-with-hypothyroidism/tips-to-relieve-constipation/

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