What is constipation?
Constipation is a common gastrointestinal condition in which the ability to pass stool is impaired, resulting in difficulty with defecation, infrequent defecation, or both. Constipation in adults is considered chronic when symptoms persist for at least three months.
Constipation is commonly categorized as either primary or secondary. Primary (idiopathic) constipation has no obvious cause, while secondary constipation does have an identifiable cause, like a disease or medication side effect. In addition to being primary or secondary, constipation can be classified into subtypes based on certain characteristics (e.g., clinical features, apparent cause, etc.).
What are the main symptoms of constipation?
Common symptoms of constipation include:
- Infrequent defecation
- Difficulty passing stools
- Excessive straining during defecation
- The feeling of a blockage in the anus and/or rectum
- Bloating
- Abdominal pain.
How is constipation diagnosed?
A diagnosis of constipation is generally based on the patient’s weekly defecation frequency, ease of defecation, sensations felt during defecation, and stool characteristics. A clinician may also collect medical history, perform lab tests, and conduct examinations to look for an underlying cause of the constipation, although in most cases none will be identified.
Different criteria exist to determine what subtype of constipation is present. The Rome IV criteria can be used to diagnose several subtypes of constipation, these being functional (primary) constipation, irritable bowel syndrome with constipation (IBS-C), opioid-induced constipation, and functional defecation disorder.[1]
What are some of the main medical treatments for constipation?
Constipation is often treated with osmotic laxatives (which pull water into the colon), stimulant laxatives (which stimulate intestinal contractions), or stool softeners.[2][3] Commonly used osmotic laxatives are polyethylene glycol (PEG), lactulose, glycerin suppositories, and magnesium hydroxide. Commonly used stimulant laxatives are bisacodyl, senna, cascara, and sodium picosulfate. A commonly used stool softener is docusate. Docusate is often prescribed in an inpatient setting[4]; however, there is inadequate evidence for its ability to ease constipation.[5] Lastly, it is important to use laxatives as prescribed by a healthcare provider, as overuse can lead to diarrhea, dehydration, and electrolyte imbalances.
Other constipation treatments include increasing dietary fiber intake, certain medications, mineral oil, and enemas. In rare cases, surgery may be indicated.
Have any supplements been studied for constipation?
A number of different fiber supplements show evidence of benefit for constipation, with psyllium being perhaps the most well-established in this regard.[6]
Probiotics (taken via capsules or fermented foods) have sometimes been found to improve symptoms of constipation.[7][8] More research is needed to determine which probiotic strains are effective, although Bifidobacterium lactis specifically appears beneficial.
Senna, an herb sometimes taken in the form of tea, has a well-established laxative effect. Cascara (Frangula purshiana) bark is another herb often taken for its laxative properties; it contains the same active chemicals (anthraquinones) as senna.
Magnesium — usually in the form of magnesium oxide or magnesium citrate — can also act as a laxative when taken in high enough amounts. However, it is important to speak to your healthcare provider before taking magnesium, as the high doses often used for constipation can lead to a harmful elevation of blood magnesium levels, especially in people with impaired kidney function.[9]
How could diet affect constipation?
Lower fiber diets tend to be associated with a higher risk of constipation,[10][11][12] and increasing fiber intake can benefit constipation[13][6] More research is needed to better understand which fiber-rich foods are best in this regard.
Prunes, being high in sorbitol, can have a laxative effect and may therefore help with constipation.[14] However, sorbitol can provoke unpleasant GI symptoms (abdominal pain, bloating) in certain individuals.[15]
A few studies have found mineral water (not to be confused with mineral oil) can be helpful for constipation, possibly due to the magnesium, sulfate, and bicarbonate it contains.[16][17]
Kiwifruit seems to be beneficial for people with constipation.[18][19][20]
Are there any other treatments for constipation?
Assuming a squatting (rather than sitting) position, such that the knees are bent sharply, can improve the ease of defecation.[21][22][21]
Some studies have found that increasing physical activity is beneficial for constipation,[23][24] though other studies have reported no effect.[25][26]
In cases of constipation due to a functional defecation disorder, biofeedback therapy can train a person to coordinate the muscles involved in passing stool, improving outcomes.[27][28]
What causes constipation?
There are many possible causes of and contributors to constipation, which means the reason for constipation varies from person to person.
A number of health conditions can cause constipation, including hypothyroidism, diabetes, hypercalcemia, intestinal stricture, multiple sclerosis, and Parkinson’s disease. Constipation can also be caused by various medications, including opioids, iron supplements, nonsteroidal anti-inflammatory drugs (NSAIDs), calcium channel blockers, antacids, antihistamines, and diuretics.
Lifestyle factors that may increase the risk of constipation include a low fiber intake,[10][11][12][29] physical inactivity,[11][30][31][29] and a low fluid intake,[32][33][34][29] although conflicting evidence exists for each of these factors.
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Frequently asked questions
Constipation is a common gastrointestinal condition in which the ability to pass stool is impaired, resulting in difficulty with defecation, infrequent defecation, or both. Constipation in adults is considered chronic when symptoms persist for at least three months.
Constipation is commonly categorized as either primary or secondary. Primary (idiopathic) constipation has no obvious cause, while secondary constipation does have an identifiable cause, like a disease or medication side effect. In addition to being primary or secondary, constipation can be classified into subtypes based on certain characteristics (e.g., clinical features, apparent cause, etc.).
Primary constipation is the medical term given to constipation without an obvious cause. It is also known as idiopathic constipation or functional constipation. There are several subtypes of primary constipation, classified according to certain gastrointestinal characteristics:
-
Normal-transit constipation: Stool moves through the colon at a normal speed. This is sometimes found to be the most common subtype.
-
Slow-transit constipation: Stool moves through the colon slowly.
-
Defecation disorder: The muscles of the pelvic floor used for defecation don’t function well.
Irritable bowel syndrome with constipation (IBS-C), meanwhile, is generally classified as a separate entity from primary constipation, despite having no obvious cause.
Common symptoms of constipation include:
- Infrequent defecation
- Difficulty passing stools
- Excessive straining during defecation
- The feeling of a blockage in the anus and/or rectum
- Bloating
- Abdominal pain.
A diagnosis of constipation is generally based on the patient’s weekly defecation frequency, ease of defecation, sensations felt during defecation, and stool characteristics. A clinician may also collect medical history, perform lab tests, and conduct examinations to look for an underlying cause of the constipation, although in most cases none will be identified.
Different criteria exist to determine what subtype of constipation is present. The Rome IV criteria can be used to diagnose several subtypes of constipation, these being functional (primary) constipation, irritable bowel syndrome with constipation (IBS-C), opioid-induced constipation, and functional defecation disorder.[1]
There are some differences in the way functional constipation is diagnosed based on whether the patient is a child or an adult. In both cases, a diagnosis will involve an evaluation by a medical professional as well as ruling out other medical explanations (like irritable bowel syndrome), but the identifying symptoms are not entirely the same.
The Rome IV criteria for diagnosing (chronic) functional constipation in adults require three months of at least two of the following symptoms:
- Straining: more than 25% of defecations.
- Lumpy or hard stools: more than 25% of defecations.
- Sensation of incomplete evacuation: more than 25% of defecations.
- Sensation of anorectal obstruction/blockage: more than 25% of defecations.
- Manual maneuvers to facilitate: more than 25% of defecations.
- Fewer than three spontaneous bowel movements per week.
The Rome IV criteria for diagnosing functional constipation in infants and children up to four years old, meanwhile, require one month of either two or fewer defecations per week or at least two of the following:
- History of excessive stool retention
- History of painful or hard bowel movements
- History of large-diameter stools
- Presence of a large fecal mass in the rectum
- Minimum of one episode/week of incontinence after the acquisition of toileting skills (toilet-trained children only)
- History of large-diameter stools that may obstruct the toilet (toilet-trained children only)
Finally, The Rome IV criteria for diagnosing functional constipation in children older than four requires at least one month of two of the following occurring at once per week:
- Two or fewer defecations in the toilet per week (children of a developmental age of at least 4 years old only)
- One or more episode(s) of fecal incontinence per week
- History of retentive posturing or excessive volitional stool retention
- History of painful or hard bowel movements
- Presence of a large fecal mass in the rectum
- History of large diameter stools that can obstruct the toilet
Constipation is often treated with osmotic laxatives (which pull water into the colon), stimulant laxatives (which stimulate intestinal contractions), or stool softeners.[2][3] Commonly used osmotic laxatives are polyethylene glycol (PEG), lactulose, glycerin suppositories, and magnesium hydroxide. Commonly used stimulant laxatives are bisacodyl, senna, cascara, and sodium picosulfate. A commonly used stool softener is docusate. Docusate is often prescribed in an inpatient setting[4]; however, there is inadequate evidence for its ability to ease constipation.[5] Lastly, it is important to use laxatives as prescribed by a healthcare provider, as overuse can lead to diarrhea, dehydration, and electrolyte imbalances.
Other constipation treatments include increasing dietary fiber intake, certain medications, mineral oil, and enemas. In rare cases, surgery may be indicated.
A number of different fiber supplements show evidence of benefit for constipation, with psyllium being perhaps the most well-established in this regard.[6]
Probiotics (taken via capsules or fermented foods) have sometimes been found to improve symptoms of constipation.[7][8] More research is needed to determine which probiotic strains are effective, although Bifidobacterium lactis specifically appears beneficial.
Senna, an herb sometimes taken in the form of tea, has a well-established laxative effect. Cascara (Frangula purshiana) bark is another herb often taken for its laxative properties; it contains the same active chemicals (anthraquinones) as senna.
Magnesium — usually in the form of magnesium oxide or magnesium citrate — can also act as a laxative when taken in high enough amounts. However, it is important to speak to your healthcare provider before taking magnesium, as the high doses often used for constipation can lead to a harmful elevation of blood magnesium levels, especially in people with impaired kidney function.[9]
Lower fiber diets tend to be associated with a higher risk of constipation,[10][11][12] and increasing fiber intake can benefit constipation[13][6] More research is needed to better understand which fiber-rich foods are best in this regard.
Prunes, being high in sorbitol, can have a laxative effect and may therefore help with constipation.[14] However, sorbitol can provoke unpleasant GI symptoms (abdominal pain, bloating) in certain individuals.[15]
A few studies have found mineral water (not to be confused with mineral oil) can be helpful for constipation, possibly due to the magnesium, sulfate, and bicarbonate it contains.[16][17]
Kiwifruit seems to be beneficial for people with constipation.[18][19][20]
Increasing fiber intake is a common recommendation for people with constipation. But the effects of fiber likely depend on what type of fiber is added.
Quite a few studies have looked at whether fiber is beneficial for constipation by assessing its ability to increase the number of stools a person passes in a week. And while a greater defecation frequency can be an indicator of benefit, it doesn’t always mean the unpleasant aspects of constipation — like abdominal pain — are actually improved.
When looking solely at patient-assessed constipation symptoms (things like stomach discomfort, bloating, painful bowel movements, and straining during defecation), several randomized controlled trials have reported no clear benefits from fiber supplementation. This was the finding of a 3-week trial using galacto-oligosaccharides (GOS; 5.5 or 11 grams per day),[35] a 2-week study using polydextrose (4, 8, or 12 grams per day),[36] and a 4-week study using wheat bran (12.5 grams of fiber per day).[37]
Conversely, some randomized controlled trials have reported improvements to patient-reported constipation symptoms from fiber supplements. Several trials on psyllium supplementation (typically in dosages of 10–20 grams of fiber per day) have reported reductions in straining[38][39] and pain during defecation.[38][40] One 4-week trial likewise found supplementation with 24 grams of pectin (a fiber found in various fruits and vegetables) led to reductions in constipation symptoms, including less bloating.[41]
This then raises the question: what is it about fibers like psyllium and pectin that makes them good at improving symptoms? The answer may be viscosity.
Fiber is believed to benefit constipation in large part by binding water in the intestines, thereby softening the stool and making it move more smoothly through the intestines. Both pectin and psyllium are very effective at binding water, which means they should increase the hydration of feces. This water-binding property, known as viscosity, varies depending on the fiber in question. Other viscous fibers and fiber-sources with evidence of benefit for constipation include flaxseeds,[42] partially hydrolyzed guar gum,[43][44] β-glucan (e.g., from oats),[45][46] and inulin.[47][48]
Finally, it’s worth noting that many types of fiber (both viscous and non-viscous) are readily fermentable by intestinal bacteria. This can result in significant gas production, potentially leading to gastrointestinal effects like flatulence and bloating, especially in susceptible individuals or when high amounts are consumed. Among the viscous fibers, inulin seems to be one of the most fermentable,[49] whereas psyllium tends to be one of the least fermentable.[50]
There isn’t much research looking at whether low-carbohydrate diets increase the risk of constipation, though a few studies suggest they can lead some people to develop constipation.
One 24-week randomized controlled trial assigned 120 people to follow either a low-carbohydrate or low fat diet for the purposes of weight loss.[51] Ultimately, more people self-reported constipation on the low-carbohydrate diet (68%) than on the low-fat diet (35%).
Another randomized controlled trial had 135 people follow either a low-carbohydrate diet or a low-fat, higher-fiber diet, with both being fairly low calorie (around 1,000–1,400 calories per day).[52] After three months, 23% of participants assigned to the low-carbohydrate diet had reported constipation, compared to only 3% on the low-fat, higher-fiber diet.
Finally, a three-month randomized controlled trial assigned 34 people with type 2 diabetes or prediabetes to either a low-carbohydrate, ketogenic diet or a calorie restricted diet based on diet guidelines by the American Diabetes Association.[53] By the end of the study, participants on the low-carbohydrate diet reported an increase in constipation symptoms.
Why exactly a low-carbohydrate diet might lead to constipation is unclear, but given that in practice such diets often lead people to eat less fiber,[54] it’s reasonable to wonder if this is a factor. In line with this, one of the three previously referenced trials assessed participants’ fiber intake, reporting that fiber intake decreased in the low-carbohydrate diet (from 17.1 to 13.9 grams per day), whereas it very slightly increased in the low-fat group (from 17.4 to 18.6 grams per day).[52]
Of course, it’s important to note that all studies were in the context of people losing weight (and all studies reported greater weight loss with the low-carbohydrate diet), meaning the low-carbohydrate diet involved calorie restriction. Whether a non-calorically reduced low-carbohydrate diet has the same effect on constipation is therefore not as clear.
Constipation is also a frequently reported side effect of ketogenic diets for childhood epilepsy.[55]
Assuming a squatting (rather than sitting) position, such that the knees are bent sharply, can improve the ease of defecation.[21][22][21]
Some studies have found that increasing physical activity is beneficial for constipation,[23][24] though other studies have reported no effect.[25][26]
In cases of constipation due to a functional defecation disorder, biofeedback therapy can train a person to coordinate the muscles involved in passing stool, improving outcomes.[27][28]
There are many possible causes of and contributors to constipation, which means the reason for constipation varies from person to person.
A number of health conditions can cause constipation, including hypothyroidism, diabetes, hypercalcemia, intestinal stricture, multiple sclerosis, and Parkinson’s disease. Constipation can also be caused by various medications, including opioids, iron supplements, nonsteroidal anti-inflammatory drugs (NSAIDs), calcium channel blockers, antacids, antihistamines, and diuretics.
Lifestyle factors that may increase the risk of constipation include a low fiber intake,[10][11][12][29] physical inactivity,[11][30][31][29] and a low fluid intake,[32][33][34][29] although conflicting evidence exists for each of these factors.
References
Examine Database References
- Fecal Weight - Marlett JA, Kajs TM, Fischer MHAn unfermented gel component of psyllium seed husk promotes laxation as a lubricant in humansAm J Clin Nutr.(2000 Sep)
- Constipation Signs and Symptoms - van der Schoot A, Drysdale C, Whelan K, Dimidi EThe effect of fiber supplementation on chronic constipation in adults: an updated systematic review and meta-analysis of randomized controlled trials.Am J Clin Nutr.(2022-Jul-11)
- Fecal Weight - Coccorullo P, Strisciuglio C, Martinelli M, Miele E, Greco L, Staiano ALactobacillus reuteri (DSM 17938) in infants with functional chronic constipation: a double-blind, randomized, placebo-controlled studyJ Pediatr.(2010 Oct)
- Constipation Signs and Symptoms - İlker Turan, Özden Dedeli, Serhat Bor, Tankut İlterEffects of a kefir supplement on symptoms, colonic transit, and bowel satisfaction score in patients with chronic constipation: a pilot studyTurk J Gastroenterol.(2014 Dec)
- Constipation Signs and Symptoms - Kinnunen O, Winblad I, Koistinen P, Salokannel JSafety and efficacy of a bulk laxative containing senna versus lactulose in the treatment of chronic constipation in geriatric patientsPharmacology.(1993 Oct)
- Constipation Signs and Symptoms - Naftali T, Feingelernt H, Lesin Y, Rauchwarger A, Konikoff FMZiziphus jujuba extract for the treatment of chronic idiopathic constipation: a controlled clinical trialDigestion.(2008)
- Constipation Signs and Symptoms - Morishita D, Tomita T, Mori S, Kimura T, Oshima T, Fukui H, Miwa HSenna Versus Magnesium Oxide for the Treatment of Chronic Constipation: A Randomized, Placebo-Controlled Trial.Am J Gastroenterol.(2021-Jan-01)
- Constipation Signs and Symptoms - Kubota M, Ito K, Tomimoto K, Kanazaki M, Tsukiyama K, Kubota A, Kuroki H, Fujita M, Vandenplas YLactobacillus reuteri DSM 17938 and Magnesium Oxide in Children with Functional Chronic Constipation: A Double-Blind and Randomized Clinical Trial.Nutrients.(2020-Jan-15)
- Constipation Signs and Symptoms - Mori S, Tomita T, Fujimura K, Asano H, Ogawa T, Yamasaki T, Kondo T, Kono T, Tozawa K, Oshima T, Fukui H, Kimura T, Watari J, Miwa HA Randomized Double-blind Placebo-controlled Trial on the Effect of Magnesium Oxide in Patients With Chronic Constipation.J Neurogastroenterol Motil.(2019-Oct-30)
- Constipation Signs and Symptoms - Collado Yurrita L, San Mauro Martín I, Ciudad-Cabañas MJ, Calle-Purón ME, Hernández Cabria MEffectiveness of inulin intake on indicators of chronic constipation; a meta-analysis of controlled randomized clinical trials.Nutr Hosp.(2014-Aug-01)