Constipation has been defined as < 3 bowel movements per week, but this is not a required criterion, and symptoms may include straining to defecate, the passage of hard stools, a sensation of incomplete evacuation, and/or the need for self-digitation to evacuate stool. Associated features include nausea, abdominal bloating, anorexia, and, in patients with fecal impaction, . Constipation is categorized as primary constipation (i.e., functional constipation) when no underlying medical cause or offending medication is identified. Primary constipation is further categorized as normal transit constipation (most common), slow transit constipation, and defecatory disorders (i.e., outlet obstruction, pelvic dyssynergia). Secondary constipation is due to an identified cause (e.g., metabolic disorders, neurological disorders, mechanical obstruction, medication use). Evaluation of constipation in adults begins with identifying red flag features for colorectal malignancy and signs of secondary constipation that may warrant specific diagnostic studies and/or immediate referral to a specialist. In the absence of such signs, a clinical diagnosis of primary constipation can be established based on the . Empiric management for primary constipation begins with nonpharmacological measures (e.g., increased fiber and fluid intake, education on avoiding stool-withholding behaviors) and bulk-forming laxatives. If symptoms persist, osmotic laxatives are recommended, followed by stimulant laxatives or intestinal secretagogues if necessary. Refractory symptoms after an appropriate trial of empiric therapy should prompt referral to gastroenterology to evaluate for disorders of defecation or colon transit. Secondary constipation is managed by treating the identified cause.
is detailed separately.
Constipation can be chronic or acute. Chronic constipation is typically classified as primary or secondary depending on the etiology. Acute constipation may be caused by lifestyle changes , hospitalization, immobility, or the acute onset of secondary causes of constipation. 
Primary constipation (functional constipation) 
Constipation with no identifiable secondary cause
- Normal transit constipation (most common): symptoms of constipation despite normal colonic transit time
Defecatory disorders (also known as outlet obstruction or pelvic floor dyssynergia): difficulty evacuating stool once it reaches the rectum
- Can manifest with prolonged straining, rectal discomfort, and trouble passing even soft stools
- May be caused by inadequate rectal propulsion, increased resistance to evacuation , or other factors
- Slow transit constipation (least common): constipation with slow colonic transit time 
Risk factors for primary constipation 
- Lifestyle: poor diet, insufficient physical activity, obesity
- Genetic predisposition
- Psychological and behavioral disorders
- Alterations in colonic dysmotility  ,
Secondary constipation 
Constipation due to a medical disorder or medication
|Etiology of secondary constipation |
|Connective tissue disorders|
Both primary and secondary constipation can cause changes in stool consistency and defecation habits.
Mechanism of altered stool consistency
- External factors such as lack of exercise or inadequate fluid and fiber intake (colon or rectum ( slow passage of ) →stool → prolonged absorption of water by the bowel → dry, hard stool → painful defecation → sensation of incomplete and irregular bowel emptying → constipation )/internal factors such as changes within the
Mechanism of altered bowel motility
- Effective peristalsis of the bowel is controlled by intrinsic (e.g., myenteric plexus) and extrinsic (e.g., sympathetic and parasympathetic) innervation.
- Any alteration in bowel innervation may lead to ineffective peristalsis.
- Drugs (e.g., calcium channel blockers, , antispasmodics, antidepressants)  → altered autonomic outflow and bowel muscle contraction 
- Endocrine pathology (e.g., downregulated bowel motility ) →
- Neurological pathology (e.g., spinal injury, enteric neuropathy) → disease or trauma of bowel innervation
- Ineffective peristalsis → difficult passage of stool regardless of stool consistency → sensation of incomplete and irregular bowel emptying
- Manage complications
Perform a clinical evaluation for constipation, including identification of:
- Clinical features or history (including medication history) suggestive of a
- No abnormal findings, no red flags
Abnormal findings or red flags
- : Refer to gastroenterology for colonoscopy to evaluate for colorectal malignancy. 
- Suspected : Identify and treat the underlying cause.
- Suspected : Refer to gastroenterology or urogynecology for anorectal function testing.
Red flags in constipation 
- Blood in stool
- Rectal bleeding
- Rectal tenesmus
- Unexplained iron deficiency anemia
- Obstructive symptoms
- Patients > 50 years of age without previous ; recent guidelines suggest 45 years as the cut-off to start screening 
- Abdominal or rectal mass
- Sudden change in bowel habits (e.g., onset of constipation without clear cause, change in stool caliber)
- Family history; of pertinent GI conditions (e.g., colorectal carcinoma, IBD)
Rome IV diagnostic criteria (adults) 
The Rome IV diagnostic criteria for primary constipation in adults are only applied if there is no suspected or identified . All criteria must be present to establish a diagnosis. 
- Symptom onset ≥ 6 months prior
The presence of ≥ 2 of the following symptoms in at least 25% of bowel movements over the last 3 months:
- Passage of spontaneous stool < 3 times/week
- Passage of hard or lumpy stool
- Sensation of anorectal obstruction
- Sensation of incomplete evacuation (rectal tenesmus)
- Straining during attempts to defecate
- Manual aid to evacuate stool
- Loose stools are rarely present except when laxatives are used.
- are not met
Physical examination 
A thorough physical examination should be performed, including the following:
- GI pathology to assess for
- Inspection of perineum and anus
Diagnostics are not routinely required for primary constipation (i.e., if the are met).
Laboratory studies 
Consider the following to evaluate foras clinically indicated.
- Blood glucose levels, HbA1c
- Thyroid function tests
- Serum PTH levels and ionized calcium
- Serum magnesium
- Age > 50 years if age-appropriate has not been performed; recent guidelines suggest starting screening at 45 years of age 
- Findings 
In the absence of colonoscopy will detect an underlying etiology.  , it is unlikely that
- Indications: suspected complications
- Modalities: CT abdomen and pelvis with IV contrast, x-ray abdomen, POCUS 
- Uncomplicated constipation: may be normal; fecal loading with/without colonic dilation may be seen 
- Features of complications: e.g., pneumoperitoenum ,
Advanced studies 
Patients with chronic primary constipation refractory to lifestyle modifications and empiric therapy should be referred to a specialist for additional workup, to identify the subtype and tailor management.
Anorectal function testing: to evaluate for defecatory disorders
- MRI) (barium or
Colon transit studies: to differentiate between normal transit constipation and slow transit constipation
- Radiopaque marker study 
- Wireless motility capsule study 
- First-line: nonpharmacological measures (e.g., high-fiber diet, increased fluid intake, and exercise) and/or trial of 
- Second-line: step-wise pharmacotherapy with laxatives from other classes
- Constipation refractory to initial pharmacological treatment after ∼ 4 weeks 
Nonpharmacological management of constipation 
- High-fiber diet: Recommend 20–35 g of dietary fiber daily, from and/or (e.g., psyllium). 
- Hydration: Encourage recommended daily fluid intake. 
- Physical activity: Encourage regular physical exercise. 
- Healthy bowel habits
- Biofeedback: Recommend in patients with defecatory disorders who are able to actively participate. 
Introduce fiber slowly (over several weeks) and ensure adequate fluid intake simultaneously to prevent cramping and bloating. 
- Patients taking and should be instructed to ensure adequate water consumption.
- Chronic; osmotic or stimulant laxative use may lead to hypokalemia (which can further reduce bowel motility) and metabolic alkalosis. 
- Stimulant laxatives should be:
- Stool softeners (e.g., docusate) should not be used for initial pharmacological treatment because their benefit has not been proven. 
|Overview of laxatives |
|Class||Agents||Mechanism of action||Adverse effects|
|Bulk-forming laxatives (fiber)|| |
|Stimulant laxatives (secretory laxatives)|| |
|Emollient stool softener|| || || |
Avoid the use of magnesium salts in patients with renal failure (magnesium is renally excreted) or cardiac dysfunction because of the risks of magnesium toxicity, other electrolyte abnormalities, and fluid shifts that could lead to volume overload. 
Intestinal secretagogues 
- Linaclotide 
- Lubiprostone 
- Adverse effects
Special patient groups
is detailed separately.
Constipation in older adults 
- Constipation is common in older adults.
- Peak prevalence: 8–40% of individuals > 70 years of age 
- More common in older adults living in institutions (e.g., long-term health care facilities) than those living independently 
Primary constipation, related to risk factors that include:
- Cognitive impairment
- Prolonged immobility (e.g., patients who are bedridden and/or in a long-term care facility)
- Stressors, social isolation 
- Impaired urge to defecate
- Secondary constipation, due to, e.g.:
Similar to the, with some special considerations
- Manage if present.
Lifestyle modifications: similar to management in all adults (see “ ” above), with some special considerations
- Fiber supplementation: Older adults are more likely to need fiber supplements to reach their daily fiber goals.
- Fluid intake
- Bowel habits: Discourage defecation in bedpans.
- Physical activity: Increased exercise does not decrease constipation in older patients diagnosed with constipation. 
- Required in most older adults with chronic constipation
- Therapy should be individualized; see “for dosages. ”
- Magnesium salts: Use with caution and avoid long-term use. 
- Consider in patients who cannot tolerate oral laxatives or those with fecal impaction.
- Enemas with mineral oil or plain warm water (without soap) are preferable. 
- Avoid phosphate enemas because of adverse effects and toxicity. 
- Consider glycerin suppositories as an alternative to enemas. 
- Inability to defecate for days or weeks
- Normal bowel sounds
- Distended, tympanitic abdomen
- DRE: hard, impacted stools distending the rectum
- Clinical diagnosis
- Abdominal x-ray (to rule out bowel perforation)
- Rule out bowel perforation.
Manual disimpaction 
- Insert lubricated gloved index finger into the rectum.
- Manually break up stool using a scissoring motion.
- Gently extract fragments using circular motions with the finger bent.
- Repeat as needed until the rectum is clear of .
- Consider procedural sedation and/or endoscopic disimpaction in severe cases.
- Administer osmotic enema (e.g., warm water enema or mineral oil enema).
- Consider the addition of stimulatory suppositories
- Prevention of recurrence
- For severe cases, consult surgery.
- Recent initiation of an opioid or dose adjustment
- New or worsening constipation
- Fecal impaction may be present
- Physical examination typically normal
- Clinical diagnosis
Rome IV diagnostic criteria for OIC
- Recent initiation of opioid treatment or a dose increase
- AND ≥ 2 of the characteristic clinical features of functional constipation:
- Passage of spontaneous bowel movement < 3 times/week
- Passage of hard or lumpy stool (more than 25% of defecations)
- Sensation of anorectal obstruction/blockage (more than 25% of defecations)
- Manual aid to evacuate stool necessary (more than 25% of defecations)
- Straining during attempts to defecate (more than 25% of defecations)
- Sensation of incomplete evacuation (more than 25% of defecations)
- Loose stools are rarely present without the use of laxatives
- Consider x-ray of the abdomen to rule out fecal impaction
- Similar to the treatment of primary constipation; see “Treatment.”
- Identify and treat any underlying organic cause.
- Lifestyle and dietary modification
- Evaluate the need for opiate therapy and discontinue/reduce dose if appropriate.
- Medical therapy