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.).

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]

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]

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.