What's Really Causing Your Constipation? 15 Common—and Not-So-Common—Reasons
- Dr. Tediana Torrens
- Nov 14, 2024
- 8 min read
Updated: Apr 30
Constipation is one of the most common digestive complaints people face, and it often goes unaddressed until symptoms become chronic or severely impact quality of life. Whether you're dealing with infrequent bowel movements, hard stools, or the constant feeling that you're not fully emptying, it's important to know that constipation isn't just uncomfortable—it can signal deeper imbalances in gut and overall health. In this article, we’ll explore the many possible causes of constipation and help you understand when it’s time to seek professional guidance.
Symptoms of Constipation
Constipation presents with symptoms that are hard to ignore, including:
Fewer than three bowel movements per week
Hard, dry, or lumpy stools
Painful or difficult stool passage
Feeling that bowel movements are incomplete
Overall reduced quality of life
These symptoms impact day-to-day well-being, making it crucial to understand the underlying causes and take proactive steps for relief. While less than 3 bowel movements per week is the true definition of constipation, less than daily bowel movements can result in negative long-term health outcomes.
Causes of Constipation
There are many possible causes that can lead to constipation, ranging from lifestyle habits to underlying health conditions. While this list is not exhaustive, it does cover most of the common causes of constipation.
Low Fiber Intake
Fiber plays a key role in maintaining healthy bowel movements. Fiber both bulks and softens stool. Bulkier stool pushes on the intestine walls, stimulating a bowel movement. A diet low in fiber can lead to slow motility and hard, dry stools that are difficult to pass.
Soluble fiber (found in oats, apples, flaxseeds, and legumes) forms a gel-like consistency that softens stool and feeds the beneficial gut bacteria. It also helps regulate cholesterol and blood sugar.
Insoluble fiber (found in whole grains, vegetables, and seeds) adds bulk to the stool and helps move waste through the intestines.
Low Hydration
Water works with fiber to keep stool soft and easier to pass. Dehydration slows the digestive process, making stools hard and dry.
Inadequate fluid intake or excessive fluid loss (from sweating, diuretics, or caffeine) can worsen constipation.
Drinking at least half your body weight in ounces of water per day (more in hot weather or with exercise) helps support healthy motility.
Sedentary Lifestyle
Physical movement stimulates the natural contractions of your intestines (peristalsis), encouraging regular bowel movements.
Research has shown that a sedentary lifestyle is associated with increased risk of constipation.
Twisting stretches and crunching movements can be particularly helpful by physically encouraging movement of stool through the intestines.
Aerobic exercise can speed up digestive processes, making bowel movements more regular.
Medication and Supplement Side Effects
Several medications can contribute to constipation by slowing gut motility or affecting fluid absorption.
Opioids: Strongly reduce peristalsis, leading to hard, compacted stools.
Proton pump inhibitors (PPIs): Lower stomach acid, impairing digestion and altering gut flora.
Iron supplements: Can lead to dark, dense, and difficult-to-pass stools.
NSAIDs and antidepressants: Affect gut movement and sensitivity.
Other drugs such as anti-nausea medications, antihistamines, and antacids can also contribute.
If you suspect your medications are causing constipation, speak with your provider about alternatives or supportive measures.
Hypochlorhydria
Stomach acid is essential for digestion and triggering appropriate digestive motility.
Low stomach acid impairs protein breakdown and slows the emptying of the stomach, affecting downstream motility.
Common causes include aging, stress, H. pylori infection, and use of antacid medications (like PPIs or H2 blockers), alcohol, and smoking.
Symptoms often include bloating, early fullness, gas, nausea, and reflux—along with constipation.
Long-term consequences of low stomach acid can include vitamin B12 and iron deficiencies.
Gastroparesis
Gastroparesis is a condition characterized by delayed stomach emptying, which can delay overall gut motility by impacting peristalsis in the intestines below.
Common causes include nerve damage or vagus nerve dysfunction, diabetes, viral infections, autoimmune disease, surgery, and medications that affect the nervous system or gut motility.
Symptoms include early satiety, bloating, nausea, vomiting, and constipation due to delayed movement of food through the digestive tract.
Constipation can result when the entire GI tract slows down, as the motility dysfunction in the stomach can affect downstream peristalsis.
Management strategies include eating smaller, low-fat meals, avoiding high-fiber solids, using prokinetic medications, and treating the underlying cause.
Food Sensitivities
Food sensitivities can trigger immune responses and inflammation in the digestive tract, slowing down motility.
Common trigger foods include dairy, gluten, eggs, soy, and corn.
Reactions may not always involve immediate symptoms, but chronic exposure can impair gut health and slow digestion.
Identifying and removing food triggers can reduce inflammation, digestive upset and restore regularity.
Testing or an elimination diet can help identify problematic foods.
IBS-C (Irritable Bowel Syndrome with Constipation)
IBS-C is a functional gut disorder characterized by constipation, bloating, and abdominal discomfort.
Often related to gut-brain axis dysfunction, meaning the communication between the gut and nervous system is disrupted.
Triggers include stress, anxiety, infections, food intolerances, and hormonal fluctuations.
Management typically includes dietary changes (like low FODMAP), stress reduction, and targeted supplements or medications.
You may also be interested in this article about IBS-friendly diets.
Intestinal Methanogen Overgrowth (IMO)
IMO is a type of gut imbalance where methane-producing organisms (like Methanobrevibacter smithii) overgrow in the intestines.
Methane gas slows gut transit time and is directly linked to constipation.
Methane also reduces serotonin production in the gut—a key player in motility.
While less common, SIBO can also result in constipation. SIBO typically presents with diarrhea.
Both IMO and SIBO are diagnosed with breath testing, with elevated methane levels in IMO and elevated hydrogen levels in SIBO.
You may also be interested in this article on SIBO & IMO.
Intestinal Candidiasis (Yeast Overgrowth)
Candida is a type of yeast that naturally lives in the gut, but when it overgrows, it can disrupt gut motility and overall function.
Contributing factors include antibiotic use, high-sugar diets, immunosuppression, and birth control pills.
Symptoms may include bloating, gas, sugar cravings, brain fog, skin issues, and constipation.
Candida overgrowth may alter gut lining integrity and promote inflammation, both of which slow down digestion.
Diagnosis is often clinical or supported by stool and blood testing. Treatment includes antifungal herbs, a low-sugar diet, and probiotics.
Hypothyroidism
An underactive thyroid slows down metabolism and digestive processes, including gut motility.
Symptoms of hypothyroidism include fatigue, weight gain, dry skin, cold intolerance, and constipation.
Even subclinical hypothyroidism (where lab levels are borderline) can lead to noticeable digestive slowdowns.
Proper thyroid hormone replacement and nutrient support (selenium, zinc, iodine) can often improve bowel regularity.
You may also be interested in this article on diets for autoimmune hypothyroidism (Hashimoto's).
Diabetes
Chronic high blood sugar damages nerves throughout the body, including those that control digestion.
Gastroparesis, a complication of diabetes, results in delayed stomach emptying and constipation.
Poor glycemic control also affects the microbiome and hydration status, worsening constipation.
Managing blood sugar and incorporating gut-supportive therapies are essential.
Histamine Intolerance
Histamine intolerance results from the accumulation of histamine in the body due to impaired breakdown.
DAO (diamine oxidase) is the main enzyme responsible for histamine breakdown in the gut. Deficiencies or dysfunction can lead to excess histamine levels.
DAO activity can be reduced by digestive disorders like SIBO, IBD, Celiac or non-Celiac gluten sensitivity.
High-histamine foods (aged cheese, wine, fermented foods and leftovers) can trigger symptoms like headaches, rashes, nasal congestion, and constipation.
Supporting gut health and reducing histamine exposure can help improve symptoms and restore bowel regularity.
Pelvic Floor Dysfunction
Weak or uncoordinated pelvic floor muscles can interfere with the ability to pass stool efficiently.
Common symptoms include straining, incomplete evacuation, and the need for manual assistance.
May be due to childbirth, surgery, trauma, or connective tissue disorders.
Pelvic floor physical therapy is often key in resolving underlying dysfunction and restoring normal bowel movements.
Hypermobility
People with hypermobility syndromes such as Ehlers-Danlos Syndrome (EDS) often experience gastrointestinal symptoms, including constipation.
These connective tissue disorders affect the muscles and nerves involved in gut motility.
Poor muscle tone and coordination in the intestines and pelvic floor can result in slowed digestion.
Common co-occurring conditions like dysautonomia, mast cell activation syndrome, or SIBO further contribute to symptoms.
Comprehensive treatment may involve pelvic floor therapy, supportive nutrition, gut motility agents, and nervous system regulation.
Lifestyle Factors
Withholding: Ignoring the urge to defecate can result in impaction, where stool becomes too hard to pass.
Traveling: Routine changes and new environments can disrupt bowel habits.
Aging and Pregnancy: Age-related slowdowns in digestion or hormone shifts during pregnancy also impact gut motility.
Other Health Conditions
Many other health conditions can slow gut motility and lead to chronic constipation.
Neurological Issues: Conditions like Parkinson’s, Alzheimer's and MS (multiple sclerosis) impact nerve signaling to the digestive system.
Autoimmune Diseases: Inflammatory conditions, like lupus, scleroderma, sarcoidosis and amyloidosis, can cause constipation via inflammation, nerve damage or motility changes.
Complications of Constipation
Without treatment, constipation can lead to:
Impaction: Severe blockage that may require medical intervention.
Hemorrhoids and Anal Fissures: Straining causes these painful conditions around the anus.
SIBO/IMO: Over time, constipation can lead to microbiota imbalances.
Rectal Prolapse: Persistent straining weakens the pelvic floor, causing rectal tissue to protrude.
Poor Mental Health: Constipation can be very uncomfortable and affect activities of daily living and social interactions. This, and the likely microbiome imbalances associated with constipation, can lead to mental health concerns like anxiety and depression.
Early Mortality: Less than daily bowel movements has been associated with increased risk of all-cause mortality.
When to See a Doctor
While constipation can be managed with dietary and lifestyle changes, certain symptoms warrant medical evaluation:
- Blood in stool or rectal bleeding
- Constant abdominal pain
- Inability to pass gas
- Vomiting or fever
- Unexplained weight loss
- Lower back pain
Constipation isn’t just a nuisance—it’s your body’s way of signaling that something in your system needs attention. With so many potential contributors, from diet and hydration to hormone balance and gut microbiome health, it’s essential to take a comprehensive approach when addressing chronic symptoms. If you’ve tried basic strategies without lasting relief, or if your symptoms are interfering with your day-to-day life, it's time to dig deeper.
Disclaimer
The information provided in this blog and throughout the website is intended for educational purposes only and should not be considered, or used as a substitute for, medical advice. The content is not meant to diagnose, treat, or cure any medical condition. This blog does not constitute the practice of any medical, nursing or other professional health care advice, diagnosis or treatment. Always consult with a qualified healthcare provider before making any changes to your health regimen or starting new treatments, and never disregard professional medical advice or delay seeking care because of something that you have read on this blog, website or in any linked materials. Your individual needs and circumstances should be evaluated by a medical professional to ensure safe and appropriate care. If you are experiencing a medical emergency, please call 911 or call for emergency medical help on the nearest telephone immediately.
References
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Jochum, Christoph. “Histamine Intolerance: Symptoms, Diagnosis, and Beyond.” Nutrients 16, no. 8 (April 19, 2024): 1219. https://doi.org/10.3390/nu16081219.
“Pelvic Floor Symptom Related Distress in Chronic Constipation Correlates With a Diagnosis of Irritable Bowel Syndrome With Constipation and Constipation Severity but Not Pelvic Floor Dyssynergia - PMC.” Accessed November 7, 2024. https://pmc.ncbi.nlm.nih.gov/articles/PMC6326213/.
Peng, Xinwei, Jibin Li, Yuwan Wu, Hongji Dai, Henry S. Lynn, and Xi Zhang. “Association of Stool Frequency and Consistency with the Risk of All-Cause and Cause-Specific Mortality among U.S. Adults: Results from NHANES 2005–2010.” Healthcare 11, no. 1 (December 22, 2022): 29. https://doi.org/10.3390/healthcare11010029.
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