Chronic Constipation Causes: Thyroid, Medicines, Pelvic Floor and What Helps

Written by AT. Chintan Dalal, N.D. · Reviewed by Dr Krushal Pabari, Clinical Team, Cure4Pain · Updated 30 October 2026

Key facts

Functional constipation affects about 1 in 10 adults worldwide, according to a 2021 meta-analysis of 45 population-based studies [1]. Long-lasting constipation is often a problem of bowel or pelvic floor function, but some causes can be checked: a 2018 review in the Medical Journal of Australia advises considering blood tests for hypothyroidism, high calcium and coeliac disease [2]. Medicines can also cause constipation, according to the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) [3]. In a 2016 study of 249 patients referred in northern India, 34% had a stool-emptying disorder of the pelvic floor [4], and in an uncontrolled 1997 German study, 63% of patients with such a disorder did not respond to psyllium fibre [5]. The 2023 American Gastroenterological Association-American College of Gastroenterology guideline strongly recommends polyethylene glycol and gives fibre and magnesium oxide conditional recommendations [6].

Scientific explainer videos in our Resources section

In our Resources section, our clinical team discusses vitamin D, its cofactors and how autoimmune, lifestyle and pain conditions develop.

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What causes constipation that lasts?

Chronic constipation is either primary, meaning a problem with how the bowel or pelvic floor works (normal transit, slow transit or a stool-emptying disorder), or secondary, for example to medicines or, rarely, a structural problem, according to a 2020 review in Gastroenterology [7]. Normal transit, meaning that bowel movement speed tests are normal, is the most common subtype, according to a 2018 review in the Medical Journal of Australia [2].

The NHS also lists low fibre, too little fluid or movement, ignoring the urge to go, and stress among causes of constipation [8]. In a hospital study from West Bengal, reported in the 2018 Indian consensus, 61.5% of patients with chronic constipation had another illness such as diabetes or hypothyroidism, and 37.7% regularly took a medicine known to cause constipation [9].

The table shows medical causes to raise with your doctor and what points to each.

Cause	What may point to it	How it is checked
Hypothyroidism	Tiredness, feeling cold, weight gain [10]	Thyroid blood tests [2]
High calcium	Fatigue; calcium or vitamin D supplements [11]	Blood calcium, then parathyroid hormone [11]
Coeliac disease	No specific clue in our sources; NIDDK lists it as a cause [3]	Coeliac blood test [2]
Diabetes	Known diabetes; constipation went with poor kidney function in people with diabetes [12]	Ask your doctor which tests apply
Medicines	Constipation that began with a new medicine [3]	Medicine review with your doctor
Pelvic floor	Long straining, incomplete emptying, using a finger to pass stool [13]	Rectal examination, then anorectal tests [2]

Can you be constipated if you go every day?

Yes, you can be constipated even if you go every day, because stool count alone does not define constipation. The 2018 Indian consensus from the Indian Motility and Functional Diseases Association and the Indian Society of Gastroenterology advises defining constipation in India by stool form and the person’s own perception, not by stool count [9]. Stool frequency is generally higher in India: of 1,404 Indian patients who reported constipation, only 507 (36%) passed fewer than three stools a week [9].

• Stool form: the 2018 Indian consensus treats Bristol types 1 to 3 as constipation-associated stools in India [9].
• Other symptoms: straining, incomplete emptying and a sense of blockage matter as much as how often you go, according to the 2020 Gastroenterology review [7].

Can thyroid problems cause constipation?

Hypothyroidism can cause constipation, but a 2005 review in the American Journal of Gastroenterology says hypothyroidism is rare among people who come to a doctor with constipation [14]. The NHS lists constipation among the common symptoms of an underactive thyroid [10], and in a small 1984 study, gut transit quickened when people with hypothyroidism received thyroid hormone [15].

• In an Indian hospital: in a study from West Bengal, reported in the 2018 Indian consensus, 10.5% of patients with chronic constipation also had hypothyroidism [9]. This shows the two occurring together, not that one caused the other.
• If you take levothyroxine: the NHS notes that calcium and iron supplements and antacids may not mix well with it [16], so ask before adding anything for your bowels.

Thyroid treatment and testing are explained on our hypothyroidism page, and food on our hypothyroidism diet article.

Does diabetes cause constipation?

Diabetes is listed as a cause of constipation, but survey data make the link less clear. The US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) lists diabetes among conditions behind constipation [3], yet in a nationally representative 2009-2010 US survey chronic constipation was not significantly more common with diabetes (14.6% against 11.2%), and among people with diabetes it was linked with poor kidney function [12].

Our type 2 diabetes and type 1 diabetes pages cover diabetes care.

Can high calcium cause constipation?

High blood calcium (hypercalcaemia) may be linked with constipation. Mild high calcium usually causes no symptoms, but a 2022 review in JAMA says it may be associated with symptoms such as fatigue and constipation in about 20% of people [11]. About 90% of cases of high calcium come from primary hyperparathyroidism or cancer, and supplements such as calcium, vitamin D and vitamin A are among the other causes [11].

If you take calcium, vitamin D or vitamin A supplements, tell your doctor about your constipation. Our articles on vitamin D toxicity and calcium supplements explain this further.

Which medicines cause constipation?

According to the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), medicines and supplements that can worsen constipation include [3]:

• Narcotic (opioid) pain medicines
• Antacids containing aluminium or calcium
• Iron supplements (see our article on iron deficiency)
• Anticholinergics and antispasmodics
• Anticonvulsants, calcium channel blockers and diuretics
• Medicines for Parkinson’s disease and some medicines for depression

NIDDK advises: “Don’t change or stop any medicine or supplement without talking with a health care professional” [17]. Your doctor may be able to adjust the dose or switch the medicine [17].

Could your pelvic floor be the problem?

Your pelvic floor could be behind long-lasting constipation, especially if you strain for a long time or feel you have not finished. In this type, called dyssynergic defaecation, the pelvic floor, abdominal wall and rectum do not work together properly during a bowel movement, according to a 2018 review in the Medical Journal of Australia [2].

• How common: in a 2016 northern Indian study, 34% of 249 referred patients had a stool-emptying disorder on at least 2 abnormal tests [4], and in a 2014 western Indian study, 40 of 99 patients with primary constipation had dyssynergic defaecation [13]. These were hospital referrals, not the general population.
• Clues: prolonged straining and incomplete emptying stood out in both the 2016 northern Indian study [4] and the 2014 western Indian study [13]. A sense of blockage and using a finger to pass stool also stood out in the western study [13], but using a finger did not differ in the northern study [4].
• Why fibre may fail: in an uncontrolled 1997 German study of 149 patients taking psyllium, 80% with slow transit and 63% with a stool-emptying disorder did not respond, while 85% with neither finding improved [5].
• Biofeedback trials: in a 2007 trial in people with pelvic floor dyssynergia, 70% reported adequate relief with biofeedback against 38% on placebo at 3 months [18]. In a 2018 trial of 100 adults with dyssynergic defaecation, home and office programmes gave similar results (68% and 70%) [19].

Anorectal testing is usually for people who do not respond to first treatments, according to the 2018 Indian consensus [9] and a 2020 review in Gastroenterology [7].

Does fibre help chronic constipation?

Fibre supplements often help chronic constipation, but not in everyone. In a 2022 meta-analysis of 16 randomised trials with 1,251 adults, 66% responded to fibre supplements against 41% on control treatment. Psyllium (isabgol) and pectin worked, more than 10 g a day and at least 4 weeks gave the best results, and wind was more common [20].

• Guidelines: the 2023 American Gastroenterological Association-American College of Gastroenterology guideline gives fibre a conditional recommendation [6]. The 2025 British Dietetic Association guideline recommends psyllium but makes no recommendation on whole diets such as a high-fibre diet, for lack of evidence [21].
• How much: NIDDK says adults should get 22 to 34 g of fibre a day from food, depending on age and sex, with plenty of liquids [17].
• When more may not help: the 2018 Indian consensus advises against fibre supplements if you already eat a high-fibre diet or bloating is prominent [9]. Many people with more severe constipation feel worse with more fibre, according to a 2005 review [14].
• Fruit trials: in a 2023 international trial, 2 green kiwifruit a day added 1.53 complete bowel movements a week from baseline in people with functional constipation; the trial was sponsored by a kiwifruit company [22]. Kiwifruit, prunes and psyllium each increased complete bowel movements in a partially randomised 2021 US trial of 79 adults with chronic constipation, with no placebo group [23].

Does drinking more water help constipation?

Drinking more water appears to help constipation mainly alongside fibre or when a person is dehydrated; on its own the evidence is thin. In a 1998 trial of 117 adults with functional constipation eating about 25 g of fibre a day, those told to drink 2 litres of mineral water had more frequent stools and used fewer laxatives than those drinking freely [24]. A 2005 review found no evidence that extra fluid helps unless a person is dehydrated [14].

The mineral content of water may matter for constipation. In a 2014 French trial of 244 women with functional constipation, with one author working for the water’s maker, 37.5% improved at 2 weeks on 1 litre a day of a magnesium sulphate-rich mineral water, against 21.1% on low-mineral water [25]. The 2025 British Dietetic Association guideline recommends high mineral water for specific constipation outcomes [21].

Does magnesium help constipation?

Magnesium oxide has helped chronic constipation in small trials, and it is the form most commonly used in adult studies, according to a 2026 systematic review, which says the results cannot be assumed to apply to other forms [26]. Magnesium oxide is used as an osmotic laxative, a type that raises the water content of stool [27] [9].

• Trials: in a 2021 trial of 90 Japanese adults with chronic constipation, 1.5 g of magnesium oxide a day (about 900 mg of elemental magnesium, by our calculation) improved symptoms in 68.3%, against 69.2% with senna and 11.7% with placebo [27]. In a 2019 trial of 34 Japanese women, overall improvement was 70.6% with magnesium oxide against 25.0% with placebo [28]. Both trials came from one Japanese medical college. A 2023 meta-analysis pooled 2 trials: 68% responded to magnesium oxide against 19% on control [29]. The 2025 British Dietetic Association guideline bases its advice on 2 trials with 94 people [21].
• Guidelines: the 2023 American Gastroenterological Association-American College of Gastroenterology guideline gives magnesium oxide a conditional recommendation [6]; the 2025 British Dietetic Association guideline says 0.5 to 1.5 g of oxide a day for at least 4 weeks may be recommended [21]. By our calculation that is about 300 to 900 mg of elemental magnesium.
• Upper limit: the US National Institutes of Health sets the upper limit for supplemental magnesium at 350 mg of elemental magnesium a day for adults, and absorption varies by form [30]. Magnesium oxide doses at the higher end of the British guideline range go above this limit, so they need medical guidance.
• Limits of the evidence: a 2026 systematic review of 7 studies of magnesium supplements in functional constipation, in infants, children and adults, found the data insufficient for a treatment recommendation [26].
• Kidney safety: in a 2019 retrospective study of 320 Japanese hospital patients prescribed magnesium oxide, 23% developed high blood magnesium, with risk rising with reduced kidney function, higher doses and longer use [31].

Low magnesium has not been shown to cause constipation. In a 2007-2010 US survey of 9,519 adults, higher dietary magnesium was linked with less constipation by stool frequency but not by stool form [32]. A survey cannot show cause. A blood test does not settle the question either: according to the NIH, less than 1% of body magnesium is in serum, and serum levels do not accurately reflect total body levels [30]. Our article on magnesium forms compares citrate, glycinate and oxide.

Which laxatives do guidelines recommend?

The 2023 American Gastroenterological Association-American College of Gastroenterology guideline gives strong recommendations to polyethylene glycol, sodium picosulfate, linaclotide, plecanatide and prucalopride [6]. The 2020 European Society of Neurogastroenterology and Motility guideline rates the evidence as high for osmotic laxatives, especially polyethylene glycol [33].

Type	Examples	2023 American guideline
Fibre	Fibre supplements	Conditional [6]
Osmotic	Polyethylene glycol	Strong [6]
Osmotic	Lactulose, magnesium oxide	Conditional [6]
Stimulant	Sodium picosulfate	Strong [6]
Stimulant	Senna	Conditional [6]
Newer medicines	Linaclotide, plecanatide, prucalopride	Strong [6]
Newer medicines	Lubiprostone	Conditional [6]

These ratings are not a treatment order. The 2018 Indian consensus starts with lifestyle changes and osmotic laxatives [9], and a 2018 review offers the newer medicines to people who do not respond to traditional laxatives [2]. A 2010 Cochrane review of 10 trials found polyethylene glycol better than lactulose for stool frequency and form [34].

Do stimulant laxatives damage the bowel with long-term use? Reviews differ. A 2024 review, with one author working for a drug company, found a lack of evidence for harm to the colon, including no convincing evidence of a link with colon cancer [35], and a 2005 review found addiction and rebound constipation unsupported [14]. A 2019 review of 5 trials concluded that the evidence does not support use beyond 4 weeks, because long-term trials are missing [36]. NIDDK advises stimulants only if constipation is severe or other treatments have not worked, and if you cannot have a bowel movement without a laxative after long use, it advises asking your doctor how to stop slowly [17].

Do exercise and toilet habits help?

Exercise probably helps constipation, though the trials are weak. A 2019 meta-analysis of 9 trials with 680 people found benefit from exercise, with a high risk of bias [37].

• Timing: NIDDK suggests trying at the same time each day, 15 to 45 minutes after breakfast, and not delaying when you feel the urge [17].
• Footstool or squatting: sources disagree. NIDDK suggests a footstool [17], and the 2018 Indian consensus describes squatting as more physiological, with limited data [9], but in a 2023 trial of 41 patients a footstool did not improve simulated defecation [38].

Can gut problems cause constipation?

Gut problems can cause constipation: IBS and coeliac disease are recognised causes, according to NIDDK [3]. Methane on a breath test is also linked with constipation (odds ratio 3.51 across 9 studies in a 2011 meta-analysis), although this does not show that it causes it [39].

Constipation with stomach pain points towards IBS: in a 2014 study from western India, constipation-type IBS and functional constipation looked alike apart from abdominal pain [13]. Our IBS page and Indian IBS diet article cover it in full.

Our gut health page explains testing for bacterial overgrowth and other gut causes.

When is constipation a red flag?

Constipation is a red flag when it comes with bleeding, weight loss or any change that is new for you, so see a doctor promptly. The US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) advises seeking care right away for [3]:

• Bleeding from the rectum or blood in the stool
• Constant abdominal pain, or being unable to pass gas
• Vomiting or fever
• Lower back pain
• Losing weight without trying

The 2018 Indian consensus lists age over 45, visible or hidden gut bleeding, a family history of colon cancer, unintended weight loss, an abdominal mass and fever as alarm features that may call for colonoscopy [9]. The NHS names constipation “that is not usual for you” among possible bowel cancer symptoms [40]. Long-standing constipation on its own has not been shown to raise the risk of colorectal cancer: in a 2013 meta-analysis, prospective studies found no increase, while case-control studies found more constipation among people with the cancer (odds ratio 1.68), which the authors say may reflect recall bias [41].

How we look at constipation that lasts at Cure4Pain

At Cure4Pain, we look at constipation in people aged 16 and over as part of the gut and thyroid picture; we do not treat acute stomach pain, which needs emergency care.

• Tests: we read a panel of about 100 markers, adding tests for your condition when clinically indicated: blood calcium and coeliac antibodies, which the 2018 review above advises considering [2]; stool tests for inflammation and parasites, a breath test for bacterial overgrowth and H. pylori where the picture calls for them; and, as the 2018 Indian consensus describes, anorectal tests if first treatments have not helped and colonoscopy for alarm features [9].
• Thyroid: TSH, FT3, FT4 and thyroid antibodies when a thyroid cause is possible. Dr Krushal Pabari manages thyroid medicine.
• Magnesium status: assessed from the overall clinical picture, not from a serum level alone.
• Food: we generally advise most patients to replace wheat with jowar, bajra or other millets as a general health measure; research supports a gluten-free diet for coeliac disease confirmed by testing [42]. As an observational clinic practice, we generally suggest limiting cruciferous (Brassica) vegetables such as cabbage and cauliflower; a 2024 review found that normal intake with enough iodine does not harm thyroid function [43]. During gut care, where raw foods are removed, whole raw fruit is allowed once in a while.
• Magnesium by mouth: mainly bisglycinate, with L-threonate or citrate as advised, counted as elemental and set for each person; other supplements are also by mouth first, with injections only when specifically needed or advised. This is a clinic choice, not a finding that one form works better: the trials above tested magnesium oxide, and those results cannot be assumed to apply to other forms [26].
• For IBS patients: we generally use these forms rather than magnesium oxide as a laxative, and isabgol and peppermint oil are not part of our usual plan. In a PubMed search in October 2026, we found no trial of citrate or bisglycinate in IBS; oxide trials were in chronic constipation, and in 2014 and 2022 IBS meta-analyses soluble fibre and peppermint oil improved symptoms, peppermint oil with very low-quality evidence [44] [45].
• Gut causes: where bacterial overgrowth is found, Dr Pabari runs supervised gut protocols with probiotics, prescribing antibiotics within the protocol when needed.
• Medicines: Dr Pabari reviews laxatives and other medicines case by case, under clinical guidance from Team Cure4Pain, in coordination with your existing consulting physician; never stop or change them on your own.
• Red flags: Dr Pabari recommends endoscopy or colonoscopy where something is suspected, and we refer to a gastroenterologist for a suspected ulcer or cancer, or for red flags such as blood in the stool, weight loss, night symptoms, a family history of bowel cancer, or new symptoms after age 50 to 60.

This is our clinic practice; individual results vary, and further studies are needed.

If constipation has lasted and you would like your tests and medicines reviewed together, you can book a consultation, online from anywhere or at our Mumbai clinic.

Frequently asked questions

What is the most common cause of chronic constipation?

Normal-transit constipation is the most common subtype, meaning that bowel movement speed tests are normal. Slow transit and stool-emptying disorders of the pelvic floor are the other main types, and medicines are a recognised secondary cause. [2] [7]

What tests should be done for chronic constipation?

A 2018 review advises considering blood tests for hypothyroidism, high calcium and coeliac disease and a rectal examination. Colonoscopy is for red flags, and anorectal tests are for people who do not respond to first treatments. [2] [9]

Is it safe to take magnesium for constipation every day?

Magnesium oxide has been tested for about 4 weeks in trials, at a dose above the NIH upper limit for supplements, so it needs medical guidance. High blood magnesium has been reported, more often with reduced kidney function, higher doses and longer use. [27] [30] [31]

Can low magnesium cause constipation?

Low magnesium has not been shown to cause constipation. A 2007-2010 US survey linked lower dietary magnesium with more constipation, but a survey cannot show cause, and serum magnesium does not reflect total body levels, according to the NIH. [32] [30]

How much water should I drink for constipation?

No amount of water is proven to help everyone with constipation. In a 1998 trial, 2 litres of mineral water a day with a 25 g fibre diet gave better results than drinking freely, and a 2005 review found extra fluid helps mainly if you are dehydrated. [24] [14]

Is isabgol good for chronic constipation?

Psyllium, which is isabgol, improved chronic constipation in a 2022 meta-analysis, and the 2025 British guideline recommends it. It can cause wind, and it often fails in slow transit and stool-emptying disorders. [20] [21] [5]

Can you become dependent on laxatives?

A 2005 review found no potential for addiction to laxatives and no rebound constipation after stopping. A 2019 review says long-term trials of stimulant laxatives are missing, so review long use with your doctor. [14] [36]

Can chronic constipation cause cancer?

Long-standing constipation has not been shown to raise colorectal cancer risk: prospective studies in a 2013 meta-analysis found no increase, although case-control studies found more constipation among people with the cancer, which the authors say may reflect recall bias. New constipation that is unusual for you, with bleeding or weight loss, still needs prompt review. [41] [40]

This article is for education and does not replace medical advice. Do not start, stop or change any medicine or supplement without medical guidance.

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