Can Anxiety Cause Diarrhea? Understanding the Gut-Brain Connection
Author:
Blossom Editorial
Oct 31, 2025
Anxiety and stress can trigger or exacerbate diarrhea through multiple gut-brain mechanisms, although other medical causes must be ruled out.
The connection between your brain and your digestive system is so strong that your gut is sometimes called your "second brain," and when you're anxious, this gut-brain communication can trigger a cascade of digestive changes, including diarrhea, cramping, and urgency.
Understanding why anxiety affects your digestive system, how to recognize anxiety-related diarrhea, and what you can do about it can help you manage this symptom and improve your quality of life.
Key Takeaways
Gastrointestinal symptoms are common in people with anxiety. Some clinic-based studies report that roughly one-third of patients with GI complaints have clinically significant anxiety, although the exact figures on anxiety-induced diarrhea aren’t established.
The gut-brain axis is a two-way communication highway where anxiety signals from your brain trigger physical changes in your digestive system, while gut problems can also worsen anxiety, creating a cycle that perpetuates both issues.
While anxiety can cause diarrhea, it's important to rule out other causes through medical evaluation, especially if you have persistent symptoms, blood in stool, unintended weight loss, or severe abdominal pain. Conditions like IBS, IBD, and food intolerances can coexist with or mimic anxiety-related digestive issues.
The Gut-Brain Connection: How Anxiety Affects Your Digestive System
Your digestive tract contains its own nervous system, called the enteric nervous system, which consists of over 100 million nerve cells lining your gastrointestinal tract from the esophagus to the rectum.
This "second brain" communicates constantly with your central nervous system through the vagus nerve, which acts like a superhighway carrying information in both directions. This bidirectional pathway explains why emotional states like anxiety can trigger physical digestive symptoms, and why digestive problems can worsen anxiety.
Although it sounds straightforward, anxiety can trigger one or more interconnected physiological processes that directly impact your digestive health.
Research published in the journal Microorganisms demonstrates that stress and anxiety can alter gut motility, increase intestinal permeability and fluid secretions, and change the balance of gut bacteria, all contributing factors to diarrhea.
Anxiety also activates mast cells, triggers hormones associated with a fight-or-flight response, and amps up neurotransmitter production, which can trigger diarrhea.
Let’s examine the various physiological processes tied to anxiety that can induce diarrhea.
Increased Gut Motility
Increased motility pushes contents through your digestive tract faster than normal, leaving less time for your colon to absorb water from waste material. The result is loose, watery stools.
Altered Intestinal Permeability
Chronic stress and anxiety can increase intestinal permeability, sometimes called "leaky gut", where the tight junctions between intestinal cells become looser. This allows more water and partially digested food particles to pass into the intestinal contents, contributing to diarrhea.
Research published in the journal Gut reveals that stress hormones like corticotropin-releasing hormone (CRH) can directly increase intestinal permeability.
Changes in Gut Secretions
Anxiety affects the secretion of fluids, mucus, and digestive enzymes throughout your gastrointestinal tract. Stress can increase fluid secretion into your intestines while simultaneously reducing absorption, contributing to watery diarrhea.
Studies demonstrate that stress hormones directly stimulate intestinal epithelial cells to secrete more chloride and water into the gut lumen, increasing stool water content.
Change in Balance of Gut Bacteria
Your gut contains trillions of microorganisms, including bacteria, viruses, and fungi, collectively known as your gut microbiome. These microbes play essential roles in digestion, immune function, and even mood regulation through their influence on neurotransmitter production.
Research increasingly shows that stress and anxiety can alter the composition of your gut microbiome, and these changes can worsen digestive symptoms, including diarrhea.
This could create a potentially vicious cycle: anxiety disrupts your gut microbiome, microbiome changes worsen digestive symptoms, and digestive problems increase anxiety.
Mast Cell Activation
Anxiety can trigger mast cells (immune cells found throughout your body), including in high concentrations in your gut, to release inflammatory substances like histamine. This mast cell activation can cause intestinal inflammation, increased fluid secretion, and faster gut transit, which can contribute to diarrhea.
Studies have found that people with anxiety disorders often have increased mast cell activation in their digestive tracts, and this activation may correlate with the severity of digestive symptoms.
The Fight-or-Flight Response
Anxiety activates your sympathetic nervous system, which is the part of your nervous system responsible for the "fight-or-flight" response. This ancient survival mechanism prepares your body to deal with perceived threats by triggering multiple physiological changes.
During this stress response, your body prioritizes functions necessary for immediate survival and deprioritizes non-essential functions like digestion.
Blood flow is redirected away from your digestive system toward your muscles and brain. Your body also releases stress hormones, including cortisol and adrenaline, which can speed up gut motility and cause your intestines to contract more forcefully and frequently.
Neurotransmitter Effects
Your gut produces and contains large amounts of neurotransmitters — the same chemical messengers your brain uses to communicate.
About 90% of the body’s serotonin is produced by enterochromaffin cells in the gut. This peripheral serotonin affects gut motility and immune function, whereas brain serotonin (the remaining 10%) is regulated separately and does not freely cross the blood–brain barrier.
During anxiety, neurotransmitter levels fluctuate, affecting both mood and digestive function. Increased serotonin in your gut can stimulate intestinal contractions and speed up the movement of contents through your digestive tract, contributing to diarrhea.
Anxiety-Related Diarrhea vs. Other Digestive Conditions
While anxiety may cause diarrhea, it's important to distinguish anxiety-related digestive symptoms from other conditions that may require different treatment approaches.
Irritable Bowel Syndrome (IBS)
IBS is a functional gastrointestinal disorder characterized by abdominal pain and changes in bowel habits, including diarrhea (IBS-D), constipation (IBS-C), or both (IBS-M). The relationship between IBS and anxiety is complex and bidirectional.
Key differences and overlaps:
IBS involves chronic symptoms (at least once weekly for 3+ months) with abdominal pain that improves with bowel movements
Anxiety can trigger IBS flares, and IBS can worsen anxiety
Many people have co-occurring anxiety disorders and IBS, with a systematic review reporting rates of around 23%
IBS diagnosis requires specific criteria and typically involves testing to rule out other conditions
Research published in Gastroenterology demonstrates that stress and anxiety are major triggers for IBS symptoms, and treating anxiety may improve IBS severity. The gut-brain axis dysfunction seen in IBS shares mechanisms with anxiety-induced digestive symptoms.
Inflammatory Bowel Disease (IBD)
IBD includes Crohn's disease and ulcerative colitis, both serious conditions involving chronic inflammation of the digestive tract. While stress and anxiety can worsen IBD symptoms, they don't cause IBD itself.
Important distinctions:
IBD involves visible inflammation and damage to intestinal tissue (seen on colonoscopy or imaging)
IBD symptoms often include blood in stool, severe abdominal pain, fever, and weight loss
IBD requires specific medical treatment, including anti-inflammatory medications
Anxiety is common in people with IBD due to the chronic illness burden, and managing anxiety can help reduce symptom severity
If you have persistent diarrhea with blood, severe pain, fever, or unintended weight loss, seek medical evaluation to rule out IBD and other serious conditions.
Food Intolerances and Sensitivities
Lactose intolerance, celiac disease, and other food sensitivities cause diarrhea through different mechanisms than anxiety, though the symptoms can be similar.
Key differences:
Food-related diarrhea typically occurs within hours of consuming trigger foods
Symptoms are consistent with specific food exposures regardless of stress levels
Testing can identify many food intolerances (lactose breath test, celiac blood tests)
Complete avoidance of trigger foods eliminates symptoms
However, anxiety can worsen symptoms from food intolerances, and the stress of managing dietary restrictions can increase anxiety, so these conditions often coexist and influence each other.
Infections and Foodborne Illness
Acute diarrhea from infections or food poisoning has a rapid onset and typically includes other symptoms like fever, vomiting, and severe cramping.
Distinguishing features:
Sudden onset (hours to days)
Often affects multiple people who consumed the same food
May include fever, vomiting, or blood in stool
Typically resolves within several days to a week
Not related to anxiety triggers or stressful situations
While anxiety doesn't cause infectious diarrhea, having an infection can certainly increase anxiety, particularly about when and where symptoms might occur.
Signs Your Diarrhea Is Anxiety-Related
Certain patterns suggest your diarrhea is primarily driven by anxiety rather than other causes:
Temporal Relationship to Stress
Anxiety-related diarrhea typically occurs during or shortly before stressful situations. You might notice diarrhea:
On weekday mornings before work, but not on relaxed weekends
Before important meetings, presentations, or social events
During exam periods or high-pressure work deadlines
When traveling or in unfamiliar situations
After receiving stressful news or during conflicts
If you can identify clear connections between your emotional state and digestive symptoms, anxiety is likely a significant contributor.
Improvement During Relaxation
Diarrhea that improves during vacations, weekends, or calm periods suggests anxiety as a primary cause. Many people with anxiety-related digestive symptoms notice that their bowel habits normalize when they're genuinely relaxed and stress-free.
Morning Predominance
Anxiety-related diarrhea often occurs in the morning, particularly after waking. This timing relates to the natural cortisol surge that happens upon waking, which can be exaggerated in people with anxiety disorders. Morning anticipatory anxiety about the day ahead can also trigger symptoms.
No Red Flag Symptoms
Anxiety-related diarrhea typically doesn't include concerning features like:
Blood in stool
Black, tarry stools
Severe abdominal pain that doesn't improve with bowel movements
Fever
Unintended weight loss
Nighttime diarrhea that wakes you from sleep
Persistent symptoms lasting more than a few weeks without anxiety triggers
The presence of any of these red flags warrants medical evaluation to rule out other conditions.
Associated Anxiety Symptoms
If your diarrhea occurs alongside other anxiety symptoms, this suggests a connection:
Racing heartbeat or palpitations
Shortness of breath or hyperventilation
Excessive sweating
Trembling or shaking
Feeling of impending doom
Difficulty concentrating due to worry
Muscle tension
The co-occurrence of multiple anxiety symptoms with diarrhea points toward anxiety as the underlying cause.
When to See a Doctor
Anxiety-related diarrhea can be a persistent issue that affects your quality of life. However, in certain situations, you must seek immediate medical evaluation:
Persistent or Severe Symptoms
Seek medical attention if you experience:
Persistent diarrhea — for example, diarrhea lasting more than 4 weeks (chronic diarrhea) or severe, very frequent episodes that cause dehydration
Severe abdominal cramping or pain
Signs of dehydration (excessive thirst, dark urine, dizziness, decreased urination)
Inability to keep fluids down due to nausea or vomiting
Red Flag Symptoms
Contact your doctor promptly if you notice:
Blood in your stool (red blood or black, tarry stools)
Fever above 101°F (38.3°C)
Unintended weight loss
Nighttime diarrhea that disrupts your sleep
New symptoms after age 50 (new chronic bowel symptoms at older ages warrant evaluation)
Severe pain that doesn't improve with bowel movements
These symptoms can indicate conditions like IBD, infections, or other serious digestive disorders that require specific medical treatment.
Impact on Quality of Life
Even if your diarrhea is anxiety-related and doesn't include concerning symptoms, you should seek help if it is:
Significantly interfering with work, school, or daily activities
Causing you to avoid social situations or travel
Leading to social isolation or relationship problems
Worsening your anxiety due to fear of symptoms
Not improving despite self-management strategies
Both anxiety and digestive symptoms can be effectively treated with professional help.
First Episode After Age 50
New onset of chronic diarrhea after age 50 warrants medical evaluation to rule out conditions that become more common with age, including colorectal cancer, microscopic colitis, and other digestive disorders.
How Blossom Health Can Help
If you're struggling with anxiety-induced diarrhea that's affecting your daily life, professional support can make a significant difference in your recovery and improve your overall quality of life. With the brain-gut connection playing a significant role, treating anxiety often improves gut health and associated symptoms.
Blossom Health provides virtual psychiatric care designed to help you effectively manage anxiety through evidence-based treatments. Our board-certified psychiatric providers can evaluate your symptoms, provide an accurate diagnosis, create personalized treatment plans, and prescribe medications when appropriate.
Getting started is straightforward: visit Blossom Health to verify we're available in your state and that we accept your insurance. You can schedule your first appointment at a time that fits your schedule, with most patients seen within days. All appointments are conducted via secure video call, allowing you to receive expert psychiatric care from home.
Medical Disclaimer
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or qualified mental health provider with any questions you may have regarding anxiety or other mental health conditions. Never disregard professional medical advice or delay seeking it because of something you have read in this article.
If you are experiencing a mental health crisis, severe anxiety, panic attacks, or thoughts of self-harm, seek immediate professional help. Contact the 988 Suicide and Crisis Lifeline by calling or texting 988, or go to your nearest emergency room.
The information provided about medications, treatments, and medical conditions is general in nature and may not apply to your individual situation. Treatment decisions should always be made in consultation with qualified healthcare providers who can evaluate your specific circumstances, medical history, and current health status.
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