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10 Differential Diagnoses for Your Constipation Patients

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10 Differential Diagnoses for Your Constipation Patients

Chronic constipation, defined by unsatisfactory, infrequent, and difficult bowel movements, affects up to 20% of adults in the United States and almost 30% of children worldwide. Regular bowel movements are essential to cleanse the colon of undigested foods, waste products, and excess bacteria.

Constipation is often a symptom of another medical problem. This article will discuss ten diagnoses that should be ruled out when working with patients with constipation. Functional testing labs can help doctors find the root cause of constipation. Ultimately, treatment of constipation relies on treating and removing the cause; dietary modifications and natural supplements can act as alternatives to pharmaceutical laxatives to provide short-term relief while the underlying cause is being addressed. 


What is Constipation? 

Constipation is a gastrointestinal condition traditionally defined as having three or fewer bowel movements weekly. However, constipation also encompasses stools that are hard, dry, and lumpy; difficult or painful to pass; or incomplete fecal evacuation. (1)

Chronic constipation is the infrequent or difficult passage of stool that persists for several weeks or longer. Chronic constipation can be divided into two categories: primary and secondary. Primary constipation, caused by disturbances in colonic motility or pelvic floor dysfunction, encompasses normal transit, slow transit, and outlet constipation. Secondary constipation is caused by underlying medical conditions or medication use. (2, 7)

Constipation Symptoms

Symptoms of constipation may include: 

  • Stools that are difficult to pass
  • Stool consistency characterized by Bristol Stool Chart types 1 and 2: separate hard lumps, like nuts, or sausage-shaped and lumpy
  • Having less than three bowel movements weekly
  • Feeling a blockage preventing a bowel movement
  • Having a sensation of incomplete bowel movements
  • Requiring an aid (e.g., laxative) to have a bowel movement 

Top 10 Differential Diagnoses for Your Constipation Patients

Because constipation is a common symptom in many disorders, it's important to distinguish between them so that you can more accurately treat it. Below are the top 10 differential diagnoses for constipation:

Intestinal Methanogen Overgrowth (IMO)

IMO is the term used to describe the overgrowth of methane-producing organisms in the gastrointestinal tract, previously called methane-type SIBO (small intestinal bacterial overgrowth). Methanobrevibacter smithii is IMO's most common causal organism; it is an archaeon and can overgrow in areas outside the small intestine. IMO causes symptoms commonly affiliated with irritable bowel syndrome-constipation (IBS-C), including abdominal pain, gas, bloating, and constipation. (3)

Small Intestinal Fungal Overgrowth (SIFO)

SIFO is the overgrowth of yeast in the small intestine. Research suggests that SIFO is responsible for over 25% of unexplained digestive symptoms, commonly including belching, bloating, indigestion, nausea, diarrhea, and gas. However, SIFO is an often overlooked cause of constipation, as well. Most SIFO cases can be attributed to an overgrowth of Candida species; symptoms accompanying digestive symptoms that can indicate Candida overgrowth include frequent skin rashes, vaginal infections, urinary tract infections, and oral thrush.

Intestinal Parasitosis

Parasitic infections account for one-fourth of all infectious diseases. While parasites can go undetected in the body without causing symptoms, gastrointestinal symptoms are a common clinical manifestation of illness. Because of the parasitic lifecycle, symptoms like gas, bloating, diarrhea, constipation, and rectal itching may occur cyclically. A 2017 study found a statistically significant higher prevalence of Blastocystis, Cryptosporidium, and Giardia in patients with IBS-C than in healthy controls.


Thyroid hormones, T4 and T3, act on every body tissue to regulate energy production and metabolism. In hypothyroidism, the thyroid underproduces thyroid hormones and causes systemic symptoms of a hypometabolic state. Hypothyroidism can decrease intestinal motility, causing constipation and other symptoms like difficulty swallowing, heartburn, and bloating.

Diabetes Mellitus

A 2016 systematic review concluded that chronic constipation is one of the most common gastrointestinal symptoms in patients with diabetes mellitus (both type 1 and type 2). High blood sugar that accompanies diabetes can cause damage to small blood vessels and nerves over time. Diabetic neuropathy, the nerve damage that occurs from impaired blood flow, reduces colonic motility, bowel transit time, rectal sensations, and the function of the external anal sphincter. All of these factors contribute to the increased risk of constipation observed in patients with diabetes. (4)

Parkinson's Disease (PD)

PD is a neurological disease defined by the loss of dopamine-producing neurons in the substantia nigra (a part of the brain). PD impacts the autonomic nervous system, the division of the nervous system that controls bodily functions we don't consciously control. Common symptoms of PD include tremors, slowed movements, muscle rigidity, and impaired cognitive function. 

Chronic constipation is one of the most common non-motor signs of PD and often presents as a prodromal symptom before the classic neurological symptoms appear. Additionally, anticholinergic and pain medications routinely prescribed to manage PD cause constipation as a frequent side effect. (5, 6)

Medication-Induced Constipation

The medications and supplements you are taking could be causing constipation as a side effect. Medications and supplements can slow intestinal motility by interfering with normal muscular contraction, creating electrolyte imbalances, and inducing intestinal inflammation. The agents most strongly associated with constipation include aluminum- and calcium-containing antacids, diuretics, opioids, antidepressants, antispasmodics, anticonvulsants, and iron-containing supplements. (7, 8

Laxatives are commonly recommended to treat constipation because they help to pass stool by acting as stool softeners or stimulating lower intestinal muscle contractions. However, laxative abuse must be considered when working up constipation. Laxative abuse can cause the intestines to lose muscle and nerve response, causing dependency on the medication and requiring higher doses to produce desired effects. (9)

Colorectal Cancer

Colorectal cancer should be considered in patients, especially those over age 50, presenting with a new-onset change in bowel habits, including constipation with rectal bleeding, blood in the stool, abdominal pain, and a frequent urge to go to the bathroom. 

Hirschsprung Disease

Hirschsprung disease, a congenital defect resulting in the absence of colonic nerve cells and impaired intestinal motility, should be considered in pediatric cases of constipation. Hirschsprung disease can cause intestinal obstructions in newborns, and milder cases can cause chronic constipation, abdominal distension, reflux, nausea, vomiting, and diarrhea in older children. (10)

Functional Constipation

Functional constipation has no identifiable underlying disease process and is the consequence of behavioral and environmental factors. Delaying defecation, a low-fiber diet, dehydration, a sedentary lifestyle, and psychological stress can all contribute to constipation. Pelvic floor dysfunction, the incoordination of pelvic floor muscles during an evacuation, can impair stool evacuation and cause constipation (7).

Functional Medicine Labs to Test for Root Cause of Constipation

Functional medicine labs can help practitioners differentiate between different conditions. Below are helpful tests to help get to the root cause of constipation:

Blood Testing

Blood work should be ordered to rule out causes of secondary constipation. A complete blood count (CBC), comprehensive metabolic panel (CMP), thyroid panel, and hemoglobin A1c (HbA1c) can assess for imbalances in blood cells, electrolytes, blood sugar, and thyroid hormones. Abnormal results can help indicate the presence of inflammation, infection, electrolyte imbalances, diabetes, and hypothyroidism. 

Comprehensive Stool Test

A comprehensive stool test utilizes multiple assessment technologies to analyze the intestinal microbiome and screen for bacterial, fungal, and parasitic infections contributing to constipation and other gastrointestinal symptoms. Additionally, stool testing includes occult blood and inflammatory markers, which, if elevated, could indicate the presence of colon cancer and the need for follow-up testing and imaging.

SIBO Breath Test

Breath testing performed at home can diagnose the presence of SIBO and IMO by measuring gases produced by intestinal organisms exhaled through the lungs. A 3-hour lactulose breath test is the preferred test to assess for IMO most accurately.

Other Tests & Imaging to Order in the Evaluation of Constipation

Depending on the patient's response to first-line therapies and lab results, imaging studies may be required to work up the cause of constipation further. Sigmoidoscopy, colonoscopy, barium enema, colonic transit, anorectal manometry, and rectal balloon expulsion are included as possible testing and imaging options to rule out gastrointestinal conditions as needed. (11)

Conventional Treatment for Constipation 

First-line conventional treatment for constipation is lifestyle modifications, including a high-fiber diet, exercise, and increased water intake. If the patient does not respond to these interventions, laxatives, like lactulose or Miralax, are prescribed. (7)

Functional Medicine Treatment for Constipation 

The resolution of constipation relies on the treatment of the specific root cause(s). Treatment options discussed below will focus on options for patients with constipation due to lifestyle factors or for symptomatic-based treatments when an underlying cause cannot be identified.

Nutrition for Constipation

A high-fiber diet is important for the maintenance of regular bowel movements. Fiber not only helps gut motility but also supports the balance of healthy bacteria in the digestive tract. Foods rich in soluble and insoluble fiber are important to incorporate into the diet. Soluble fiber dissolves in water, creating a gel that bulks stool. Insoluble fiber acts as roughage, promoting the passage of feces through the intestines. Whole fruits, vegetables, grains, and legumes have high amounts of soluble fiber. Foods high in insoluble fiber include skins and seeds of fruits and vegetables, popcorn, nuts, and dried fruits. (12)

Research shows that low water intake is associated with an increased prevalence of constipation. One study revealed that inadequate fluid intake was associated with double the risk of constipation in the elderly. General recommendations suggest drinking 0.5-1 ounce per pound of body weight daily to prevent dehydration.

Supplements & Herbs for Constipation

Psyllium husk is a bulk-forming laxative and supplemental fiber source effective in treating constipation. Research shows that it is 3.4 times more effective than wheat bran in increasing stool output in constipated patients.

Cathartic, stimulating laxatives containing anthraquinones can help people with atonic constipation. Cathartic herbal laxatives include senna, aloe latex, rhubarb, and cascara. Cathartic herbs should not be used for more than ten consecutive days to prevent dependency, electrolyte imbalances, and the potential risk of melanosis coli and colorectal cancer. (13)

Magnesium oxide and citrate act as osmotic laxatives, drawing water into the colon to alleviate constipation. Magnesium may be a safer alternative to other herbal and prescription laxatives.

Complementary and Alternative Medicine for Constipation

Acupuncture has been deemed safe and effective in the treatment of constipation. The overall efficacy rate of acupuncture for chronic functional constipation was 52%, and electroacupuncture efficacy rates have been reported to be as high as 94.4%. Acupuncture improves defecation frequency, abdominal pain, evacuation difficulty, laxative dependency, and quality of life. (13)

Massage has also been shown to increase the frequency of bowel movements and relieve constipation-associated abdominal pain (13).

Pelvic floor physical therapy focuses on retraining the pelvic floor muscles to relieve symptoms of pelvic floor dysfunction, like constipation. Biofeedback-based physical therapy has shown a success rate of up to 90% in patients with pelvic floor dysfunction (7).

Bowel retraining is a program that reestablishes control over regular bowel movements. It can benefit patients with constipation due to lifestyle behaviors, stress, and laxative abuse. Bowel retraining programs help to teach patients strategies to improve stool consistency and stimulate regular and daily elimination.


Constipation is the infrequent and difficult passage of stool. Underlying medical conditions, lifestyle factors, and medications can cause constipation. You may be constipated if you do not have at least one bowel movement daily. This article discussed ten causes of constipation that should be considered for patients experiencing constipation. Natural therapies and dietary modifications can help normalize bowel movement frequency and consistency during a diagnostic evaluation to relieve constipation symptoms. For functional medicine approaches to underlying causes of constipation discussed in this article, check out the Rupa Magazine for more information.

The information provided is not intended to be a substitute for professional medical advice. Always consult with your doctor or other qualified healthcare provider before taking any dietary supplement or making any changes to your diet or exercise routine.
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Lab Tests in This Article


1. Definition & Facts for Constipation. (2022, July 21). National Institute of Diabetes and Digestive and Kidney Diseases.

2. Constipation. (2021, August 31). Mayo Clinic.

3. Takakura, W., & Pimentel, M. (2020b). Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome – An Update. Frontiers in Psychiatry, 11.

4. Ihana-Sugiyama, N., Nagata, N., Yamamoto-Honda, R., et al. (2016). Constipation, hard stools, fecal urgency, and incomplete evacuation, but not diarrhea is associated with diabetes and its related factors. World Journal of Gastroenterology, 22(11), 3252.

5. Yu, Q., Yu, S., Zuo, L., et al. (2018). Parkinson disease with constipation: clinical features and relevant factors. Scientific Reports, 8(1).

6. Gelber, R.P., Launer, L.J., & White, L.R. (2012). The Honolulu-Asia Aging Study: Epidemiologic and Neuropathologic Research on Cognitive Impairment. Current Alzheimer Research, 9(6), 664–672.

7. Jamshed, N., Lee, Z.E., & Olden, K.W. (2011). Diagnostic approach to chronic constipation in adults. American Family Physician, 84(3), 299–306.

8. Murdock, J. (2022, March 11). 8 Types of Medications That Can Cause Constipation. Good Rx.

9. Cornell Health. (2019). Laxative Use: What to Know.

10. Lotfollahzadeh, S., Taherian, M., & Anand, S. (2023). Hirschsprung Disease. StatPearls Publishing.

11. Bharucha, A.E., Dorn, S.D., Lembo, A., et al. (2013). American Gastroenterological Association Medical Position Statement on Constipation. Gastroenterology, 144(1), 211–217.

12. Foods for Constipation. (2022, November 1). Johns Hopkins Medicine.

13. Sun, N.X., & Yin, J. (2015). Complementary and Alternative Therapies for Chronic Constipation. Evidence-Based Complementary and Alternative Medicine, 2015, 1–11.

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