🩺 Constipation

## Overview Constipation is one of the most common gastrointestinal complaints worldwide. It is generally defined as having fewer than three bowel movements per week, often accompanied by hard or lumpy stools, straining, a sensation of incomplete evacuation, or a feeling of anorectal blockage. The Rome IV criteria further refine the diagnosis of functional constipation by requiring that symptoms be present for at least three months with onset at least six months prior to diagnosis [1]. Globally, the estimated prevalence of chronic constipation in the community ranges from 2% to 27%, depending on the definition used, with a pooled prevalence of approximately 14% [2]. Women are affected roughly twice as often as men, and prevalence increases with age — particularly after 65 years. In the United States alone, constipation accounts for approximately 2.5 million physician visits and over 700,000 emergency department visits annually [3]. People search for information about constipation because it is uncomfortable, sometimes alarming, and frequently undertreated. Many individuals self-manage for weeks before seeking medical advice, making reliable, evidence-based information essential. **ICD-10 code:** K59.0 (Constipation, not elsewhere classified) ## Common Causes Constipation has a broad differential diagnosis. Causes can be grouped by mechanism and are listed here roughly in order of frequency in outpatient settings. ### 1. Functional (Primary) Constipation The most common type. Sub-classified into: - **Normal-transit constipation** — stool moves at a normal rate through the colon, but patients perceive difficulty. Often associated with hard stools and psychosocial distress. - **Slow-transit constipation** — reduced colonic motility, often due to decreased interstitial cells of Cajal or impaired enteric neural signaling. Patients may go many days without any urge to defecate [3]. - **Dyssynergic defecation (pelvic floor dysfunction)** — failure of coordinated relaxation of the puborectalis muscle and external anal sphincter during attempted evacuation. Affects up to 40% of patients referred for chronic constipation [1]. ### 2. Dietary and Lifestyle Factors Insufficient dietary fiber (the average Western adult consumes 12–18 g/day versus the recommended 25–30 g/day), inadequate fluid intake, and physical inactivity all contribute to slower colonic transit. A 2005 systematic review challenged some popular beliefs — for instance, evidence that general dehydration alone causes constipation is weak — but low fiber intake is a well-established risk factor [4]. ### 3. Medication-Induced Constipation Drug-induced constipation is extremely common. Key classes include: - **Opioids** — activate mu-receptors in the enteric nervous system, reducing peristalsis and increasing fluid absorption. Opioid-induced constipation (OIC) affects 40–80% of opioid users. - **Anticholinergics** — reduce colonic motility (e.g., antihistamines, tricyclic antidepressants, antipsychotics). - **Calcium channel blockers** — particularly verapamil. - **Iron supplements** — directly irritate the mucosa and alter stool consistency. - **Calcium and aluminum-containing antacids.** ### 4. Metabolic and Endocrine Disorders - **Hypothyroidism** — reduced thyroid hormone slows gastrointestinal motility. - **Diabetes mellitus** — autonomic neuropathy impairs colonic and rectal function. - **Hypercalcemia** — decreases smooth-muscle contractility. - **Hypokalemia** — impairs neuromuscular function in the bowel. ### 5. Neurological Conditions Parkinson disease, multiple sclerosis, spinal cord injury, and stroke can all impair the complex neural control of defecation [3]. ### 6. Structural and Obstructive Causes Colorectal cancer, strictures, rectocele, and rectal prolapse may cause mechanical obstruction. While less common, these must be excluded — especially in patients over 50 with new-onset constipation or alarm features. ### 7. Pregnancy Progesterone-mediated smooth-muscle relaxation, iron supplementation, and mechanical compression by the enlarging uterus all contribute. Up to 40% of pregnant individuals experience constipation. ## RED FLAGS Seek **immediate medical attention** (emergency department or call emergency services) if constipation is accompanied by any of the following: - **Severe, sudden abdominal pain** or rigidity — may indicate bowel obstruction, perforation, or volvulus - **Inability to pass gas along with absent bowel movements** — classic sign of complete bowel obstruction - **Rectal bleeding with hemodynamic instability** (dizziness, rapid heart rate, fainting) - **Persistent vomiting**, especially feculent vomiting - **High fever** (≥ 38.5 °C / 101.3 °F) with abdominal distension - **Signs of peritonitis** — rebound tenderness, guarding, board-like abdomen Seek **urgent evaluation** (same-day or next-day physician visit) for: - Unintentional weight loss (≥ 5% body weight over 6–12 months) - New-onset constipation in adults over 50 without an obvious cause - Persistent rectal bleeding or iron-deficiency anemia - Family history of colorectal cancer or inflammatory bowel disease with a change in bowel habits - Progressively worsening constipation unresponsive to standard therapy over 4–6 weeks - Severe abdominal bloating with palpable fecal loading ## Self-Care at Home Evidence-based non-pharmacological measures should be the first line of management for mild to moderate constipation. ### Increase Dietary Fiber Gradually Aim for 25–30 g of fiber per day from whole grains, fruits, vegetables, and legumes. Soluble fiber (e.g., psyllium) generally has stronger evidence than insoluble fiber (e.g., wheat bran) for improving stool frequency and consistency. Increase intake gradually over 2–3 weeks to minimize bloating and gas [5]. ### Maintain Adequate Hydration While overhydration does not accelerate colonic transit, inadequate fluid intake may worsen constipation, especially when fiber intake is increased. A reasonable target is approximately 1.5–2 liters of non-caffeinated fluids daily for most adults. ### Regular Physical Activity Moderate exercise — such as brisk walking for 30 minutes most days — has been associated with improved bowel function, although the evidence from randomized trials is modest [4]. Exercise may benefit constipation primarily through its effects on overall well-being and reduced colonic transit time. ### Establish a Bowel Routine Encourage attempting a bowel movement at the same time each day, ideally 15–30 minutes after a meal to take advantage of the gastrocolic reflex. Allowing adequate, unhurried time on the toilet is important. ### Optimize Toileting Posture Elevating the feet on a small stool to achieve a squatting-like position (approximately 35° hip flexion) straightens the anorectal angle and may facilitate easier evacuation. A small randomized trial found that a defecation postural modification device reduced straining and improved the sensation of complete emptying. ### Prunes (Dried Plums) Dried plums (approximately 50 g twice daily) have shown efficacy comparable to psyllium in a randomized controlled trial for chronic constipation, likely due to their sorbitol content and fiber [5]. ### Abdominal Massage Gentle clockwise abdominal massage following the course of the colon has shown benefit in some studies, particularly in elderly and neurologically impaired patients. ## OTC Medications That Help Over-the-counter (OTC) laxatives are appropriate for short-term use or, in some cases, for longer-term management under clinician guidance. They are classified by mechanism of action. | Class | Example(s) | Typical Adult Dose | Notes | |---|---|---|---| | **Bulk-forming laxatives** | Psyllium (Metamucil), Methylcellulose (Citrucel) | Psyllium: 3.4–6.8 g/day in divided doses with ≥ 240 mL water | First-line for chronic constipation. Must be taken with adequate fluid to avoid obstruction. Avoid in patients with strictures or dysphagia. | | **Osmotic laxatives** | Polyethylene glycol 3350 (MiraLAX), Lactulose, Magnesium hydroxide (Milk of Magnesia) | PEG 3350: 17 g (1 capful) in 240 mL water once daily | PEG 3350 has strong evidence from multiple RCTs [5]. Magnesium-based products should be avoided in renal impairment. Lactulose may cause significant bloating. | | **Stimulant laxatives** | Bisacodyl (Dulcolax), Sennosides (Senokot) | Bisacodyl: 5–10 mg orally once daily; Senna: 15–30 mg sennosides once or twice daily | Effective for short-term use. Long-standing concerns about dependency and "melanosis coli" are largely unfounded, but prolonged daily use should still be discussed with a clinician [4]. | | **Stool softeners** | Docusate sodium (Colace) | 100 mg twice daily | Evidence for efficacy is weak. A randomized trial found docusate no better than placebo. Generally considered less effective than osmotic or stimulant laxatives [5]. | | **Lubricant laxatives** | Mineral oil | 15–45 mL orally once daily | May reduce absorption of fat-soluble vitamins. Risk of lipoid aspiration pneumonia — avoid in elderly, those with dysphagia, or bedridden patients. Not for long-term use. | | **Rectal agents** | Glycerin suppositories, Bisacodyl suppositories, Sodium phosphate enemas | Glycerin: 1 suppository rectally as needed; Fleet enema: 1 unit rectally | Useful for acute relief or fecal impaction. Sodium phosphate enemas can cause dangerous hyperphosphatemia in elderly or renally impaired patients — use with caution. | **General guidance:** Start with the least aggressive option (fiber → osmotic → stimulant). If OTC measures fail after 2–4 weeks of consistent use, consult a healthcare provider [5]. ## Prescription Options Prescription medications are typically considered when lifestyle modifications and OTC therapies have not provided adequate relief, or when constipation is secondary to a specific cause such as opioid use. | Class | Example(s) | Indication | Notes | |---|---|---|---| | **Chloride channel activators** | Lubiprostone (Amitiza) | Chronic idiopathic constipation (CIC), OIC | 24 mcg twice daily for CIC. FDA-approved. May cause nausea. Contraindicated in suspected mechanical bowel obstruction. | | **Guanylate cyclase-C agonists** | Linaclotide (Linzess), Plecanatide (Trulance) | CIC, IBS-C | Linaclotide: 145 mcg (CIC) or 290 mcg (IBS-C) once daily on empty stomach. Diarrhea is most common adverse effect. Contraindicated in children < 2 years (black box warning) [6]. | | **Serotonin 5-HT₄ agonists** | Prucalopride (Motegrity) | CIC | 2 mg once daily. Prokinetic that accelerates colonic transit. Well-tolerated; headache is the most common side effect. Studied in large RCTs with sustained efficacy over 12 weeks [3]. | | **Peripherally acting mu-opioid receptor antagonists (PAMORAs)** | Naloxegol (Movantik), Methylnaltrexone (Relistor), Naldemedine (Symproic) | Opioid-induced constipation | Block opioid effects on gut without reversing central analgesia. Naloxegol: 25 mg once daily. Contraindicated in known or suspected GI obstruction [6]. | | **Biofeedback therapy** | N/A (behavioral) | Dyssynergic defecation | Not a drug but a first-line prescription-level treatment for pelvic floor dyssynergia. Randomized trials show superiority over laxatives for this subtype [1]. | **Who prescribes:** Primary care physicians may initiate most of these therapies. Referral to a gastroenterologist is appropriate when empiric treatment fails, when dyssynergic defecation is suspected, or when further diagnostic workup (e.g., anorectal manometry, colonic transit study) is needed. ## Lab Tests Typically Ordered Routine laboratory testing is not always necessary for straightforward constipation, but may be warranted when the history suggests a secondary cause or when red-flag features are present. | Test | Rationale | |---|---| | **Complete blood count (CBC)** | To detect anemia (possible colorectal malignancy or chronic blood loss). [See /tests/complete-blood-count](/tests/complete-blood-count) | | **Thyroid-stimulating hormone (TSH)** | To rule out hypothyroidism as a reversible cause. [See /tests/thyroid-stimulating-hormone](/tests/thyroid-stimulating-hormone) | | **Basic metabolic panel (BMP)** | To assess serum calcium (hypercalcemia), potassium (hypokalemia), creatinine (renal function), and glucose (diabetes). [See /tests/basic-metabolic-panel](/tests/basic-metabolic-panel) | | **Fasting glucose or HbA1c** | If diabetes-related autonomic neuropathy is suspected. [See /tests/hemoglobin-a1c](/tests/hemoglobin-a1c) | | **Fecal occult blood test (FOBT) / FIT** | To screen for occult bleeding in patients with new-onset constipation, especially ≥ 45 years. [See /tests/fecal-occult-blood-test](/tests/fecal-occult-blood-test) | | **Colonoscopy** | Not a lab test per se, but indicated in patients with alarm features, those ≥ 45 who are not current with colorectal cancer screening, or when structural pathology is suspected. | | **Colonic transit study (Sitzmarker study)** | Radio-opaque markers are ingested and abdominal X-rays are taken after 5 days. Useful to distinguish slow-transit constipation from dyssynergic defecation [3]. | | **Anorectal manometry and balloon expulsion test** | To diagnose pelvic floor dyssynergia. Considered when there is an inadequate response to empiric laxative therapy [1]. | ## Special Populations ### Children Functional constipation is common in children, affecting an estimated 3–10% of pediatric visits. The Rome IV criteria for children differ from adult criteria. Key considerations: - **First-line therapy** is behavioral: regular toileting habits, adequate fluid, and age-appropriate fiber intake. - **PEG 3350** is the best-studied osmotic laxative in children and is generally recommended as first-line pharmacotherapy for fecal impaction (disimpaction) and maintenance. Dosing should be determined by the child's physician based on age and weight — do not extrapolate adult dosing [7]. - **Stimulant laxatives** (senna, bisacodyl) may be used short-term under medical supervision for disimpaction. - **Lactulose** is an alternative osmotic agent commonly used in infants. - **Linaclotide and lubiprostone** are **not approved** for use in children under 18 years (linaclotide carries a black box warning for children < 2 years due to deaths in juvenile animal studies). - Constipation in neonates or children under 1 year warrants prompt medical evaluation to exclude Hirschsprung disease and other anatomic abnormalities. *NICE guideline CG99 provides a comprehensive, evidence-based framework for managing constipation in children and young people* [7]. ### Pregnancy Constipation affects up to 40% of pregnancies. Hormonal changes (elevated progesterone), reduced physical activity, iron supplementation, and uterine compression all contribute. - **First-line:** Dietary fiber, hydration, and physical activity. - **Bulk-forming laxatives (psyllium):** Generally considered safe; not systemically absorbed. - **PEG 3350:** Minimal systemic absorption; commonly used in pregnancy when fiber alone is insufficient. Generally considered compatible with pregnancy. - **Docusate sodium:** Considered safe but of questionable efficacy. - **Stimulant laxatives (senna, bisacodyl):** May be used occasionally. Prolonged use is not recommended due to theoretical concerns about electrolyte imbalance, though evidence of harm is limited. - **Mineral oil:** Avoid — may reduce fat-soluble vitamin absorption. - **Castor oil:** **Contraindicated** — may stimulate uterine contractions. - **Lubiprostone:** FDA Pregnancy Category C; limited human data — generally avoided. - **Linaclotide, prucalopride:** Insufficient human pregnancy data; avoid unless clearly necessary and directed by a specialist. *ACOG recommends starting with increased fiber and fluids and escalating to PEG 3350 or a stimulant laxative if needed.* ### Elderly Constipation prevalence rises sharply after age 65, affecting up to 50% of nursing home residents. Contributing factors include polypharmacy, reduced mobility, inadequate dietary intake, and neurodegenerative conditions. - **PEG 3350** is well-studied and generally well-tolerated in elderly adults. - **Avoid sodium phosphate enemas** in elderly patients or those with renal impairment due to risk of severe hyperphosphatemia, hypocalcemia, and death. The FDA has issued warnings regarding this risk. - **Avoid mineral oil** in those with swallowing difficulties (aspiration risk). - **Fecal impaction** is common and may present atypically with overflow diarrhea, confusion, or urinary retention. Manual disimpaction or enema therapy may be required. - Always review the medication list — polypharmacy is the most correctable cause of constipation in this population. ### Athletes While regular exercise is generally protective against constipation, endurance athletes may paradoxically experience constipation due to: - **Dehydration** during prolonged training or competition - **Dietary restriction** (low-residue diets before events) - **NSAID use** — may alter gut motility and microbiome - **Relative energy deficiency in sport (RED-S)** — caloric restriction can slow gut transit Adequate hydration, fiber-rich fueling strategies, and awareness of RED-S are important preventive measures in this population. ## When to Escalate Use the following thresholds to determine the urgency of medical evaluation: ### Same-Day Primary Care or Telehealth Visit - Constipation lasting > 2 weeks despite consistent OTC measures - New constipation coinciding with a new medication - Mild rectal bleeding (small amounts of bright red blood on tissue only, no other red flags) - Constipation alternating with diarrhea (to evaluate for IBS or other conditions) ### Urgent Care (Within 24 Hours) - Moderate abdominal pain with distension and no bowel movement for ≥ 5 days - Constipation with new-onset urinary retention - Constipation in a patient with known inflammatory bowel disease or prior abdominal surgery - Elderly patient with abrupt change in bowel habits and signs of fecal impaction ### Emergency Department (Immediately) - Severe abdominal pain with rigidity or rebound tenderness - Complete inability to pass stool or gas for > 24 hours with vomiting and distension (suspected bowel obstruction) - Signs of shock: hypotension, tachycardia, altered consciousness - Significant rectal bleeding with dizziness, pallor, or syncope - Feculent vomiting **Important:** These thresholds are general guidelines. Individual clinical context always matters. When in doubt, err on the side of seeking earlier evaluation. This article is for informational purposes and does not replace personalized medical advice from a qualified healthcare provider. ## References [1] Bharucha AE, Lacy BE. Mechanisms, Evaluation, and Management of Chronic Constipation. *Gastroenterology*. 2020;158(5):1232-1249.e3. PMID:31945360. [2] Suares NC, Ford AC. Prevalence of, and risk factors for, chronic idiopathic constipation in the community: systematic review and meta-analysis. *Am J Gastroenterol*. 2011;106(9):1582-1591. PMID:21606976. [3] Camilleri M, Ford AC, Mawe GM, et al. Chronic constipation. *Nat Rev Dis Primers*. 2017;3:17095. PMID:29239347. [4] Müller-Lissner SA, Kamm MA, Scarpignato C, Wald A. Myths and misconceptions about chronic constipation. *Am J Gastroenterol*. 2005;100(1):232-242. PMID:15654804. [5] Wald A. Constipation: Advances in Diagnosis and Treatment. *JAMA*. 2016;315(2):185-191. PMID:26757467. [6] U.S. Food and Drug Administration. Prescribing information for linaclotide (Linzess), lubiprostone (Amitiza), naloxegol (Movantik). Available at: https://www.accessdata.fda.gov/scripts/cder/daf/. Accessed 2026. [7] National Institute for Health and Care Excellence (NICE). Constipation in children and young people: diagnosis and management. Clinical guideline [CG99]. 2010 (updated 2017). Available at: https://www.nice.org.uk/guidance/cg99. [8] Bharucha AE, Dorn SD, Lembo A, Pressman A. American Gastroenterological Association Medical Position Statement on Constipation. *Gastroenterology*. 2013;144(1):211-217. PMID:23261064. [9] Ford AC, Moayyedi P, Lacy BE, et al. American College of Gastroenterology Monograph on the Management of Irritable Bowel Syndrome and Chronic Idiopathic Constipation. *Am J Gastroenterol*. 2014;109(Suppl 1):S2-S26. PMID:25091148.