5 Ways Anxiety Can Affect Gut Health

The phrase “gut feeling” reflects more than intuition—it points to the powerful link between the brain and the digestive system. Anxiety and stress trigger physical changes in the gastrointestinal (GI) tract through the gut–brain axis, a communication system that relies on hormones, nerves, and gut microbes.

Research shows that these interactions can alter motility, disrupt microbiota, heighten pain sensitivity, and contribute to chronic digestive conditions. Understanding how anxiety impacts the gut is critical, especially as up to 40% of Americans report stress-related stomach issues during their lifetime.¹

Here are 5 ways anxiety can influence digestive health.

Altered Gut Motility

Anxiety activates the sympathetic nervous system—the body’s “fight-or-flight” response—which diverts blood flow away from digestion toward muscles and the brain.² This can disrupt normal intestinal contractions, causing food to move either too quickly, leading to diarrhea, or too slowly, causing constipation.

The effect on gut motility is often immediate. For example, a stressful presentation or major life event may bring on sudden cramps or diarrhea, but chronic anxiety has longer-lasting consequences. Cuckoo Choudhary, MD, professor of medicine at Thomas Jefferson University and gastroenterologist at Jefferson Health, said stress “can alter the gastrointestinal motility, which means the ability of the small bowel and the colon to squeeze and move forward the undigested food and waste products.”³ Over time, repeated motility disruptions can lead to persistent bloating, irregular bowel habits, and abdominal discomfort.

These changes are not just inconvenient—they can worsen conditions such as irritable bowel syndrome (IBS), where abnormal muscle contractions already play a central role.⁴ For patients, managing anxiety can be as important as dietary adjustments in restoring gut rhythm.

Increased Intestinal Inflammation

Stress-related changes in the gut go beyond movement. Anxiety can directly fuel inflammation in the digestive tract by increasing gut permeability, sometimes called “leaky gut.”⁵ This occurs when stress hormones like cortisol and adrenaline weaken the intestinal barrier, allowing bacteria and toxins to seep into circulation and trigger immune responses.

Studies have shown that both acute stressors, such as public speaking, and chronic ones, like marital strain, increase intestinal permeability. Once the barrier is compromised, pro-inflammatory bacteria can thrive, compounding discomfort with symptoms like cramping, diarrhea, or nausea. Inflammation of this kind not only worsens existing conditions like inflammatory bowel disease (IBD) but also creates a cycle in which stress and gut dysfunction reinforce one another.³

Disrupted Gut Microbiome

The trillions of microbes in the gut play an essential role in digestion, immune function, and even mood regulation. Anxiety disrupts this balance, encouraging harmful bacteria to grow while reducing populations of beneficial species such as Lactobacillus and Bifidobacterium.⁶

University studies have found that as student stress increased during exams, the amount of bad bacteria in the gut increased—a condition known as dysbiosis.³ Dysbiosis has been linked to everything from changes in food cravings to heightened risk of autoimmune disease.⁵

Diet also plays a role: stress encourages cravings for processed or sugary foods, which further nurture inflammatory bacteria.³ Over time, this can contribute to metabolic conditions, obesity, and chronic GI issues. Supporting microbial diversity through fiber, plant-based diets, and probiotic-rich foods is one strategy clinicians recommend for counteracting stress-induced microbiome disruption.

Heightened Sensitivity

For many people with functional GI disorders, the gut is not only reactive but also hypersensitive. Stress and anxiety can “increase what we call visceral perception, [which] means the gut becomes more sensitive to pain and to extraneous stimuli,” according to Choudhary, meaning the brain interprets normal gut activity as painful. This explains why a bloated stomach or mild cramp can feel more severe during times of stress.

Harvard experts have noted that psychosocial factors “influence the actual physiology of the gut, as well as symptoms,” making pain seem worse even without visible structural disease.⁷ Patients with IBS, for example, often report heightened discomfort during stressful periods, despite no changes in bowel tissue.

This heightened sensitivity creates a feedback loop: anxiety amplifies gut symptoms, and worsening gut symptoms increase anxiety. Breaking this cycle often requires approaches that address both sides of the gut–brain axis, such as cognitive behavioral therapy, mindfulness practices, and medications when necessary.

Development of Chronic GI Conditions

Occasional nausea or diarrhea linked to anxiety usually resolves once stress subsides, but when stress is ongoing, the risk of chronic gastrointestinal disorders rises. Up to 40% of Americans experience anxiety-related stomach issues, and chronic exposure can increase the likelihood of developing IBS, gastroesophageal reflux disease (GERD), and indigestion.^1,8

IBS in particular highlights the role of stress. Although not caused solely by anxiety, flare-ups are strongly linked to emotional distress, with early-life stress, severe infections, and changes in gut microbes all being factors that increase IBS risk.⁴

Once the condition is established, stress often makes symptoms more frequent and severe. In some cases, stress may even act as an environmental trigger for IBDs in genetically predisposed individuals.³ This underscores the importance of comprehensive care that addresses both mental health and gut health together.

References

1. Understanding the link between anxiety and gastrointestinal disorders. Doral Health & Wellness. Accessed September 26, 2025. https://doralhw.org/link-anxiety-and-gastrointestinal-disorders/
2. Greenwald HS. How stress can affect your digestive health. Temple Health. August 7, 2025. Accessed September 26, 2025. https://www.templehealth.org/about/blog/how-stress-can-affect-your-digestive-health
3. Lopez J, Williams C. How stress is affecting your gut health—and what you can do to manage it. Jefferson Health. May 30, 2024. Accessed September 26, 2025. https://www.jeffersonhealth.org/your-health/living-well/how-stress-affects-your-gut-health
4. Irritable bowel syndrome. Mayo Clinic. Updated October 11, 2024. Accessed September 26, 2025. https://www.mayoclinic.org/diseases-conditions/irritable-bowel-syndrome/symptoms-causes/syc-20360016
5. Madison A, Kiecolt-Glaser JK. Stress, depression, diet, and the gut microbiota: human-bacteria interactions at the core of psychoneuroimmunology and nutrition. Curr Opin Behav Sci. 2019;28:105-110. doi:10.1016/j.cobeha.2019.01.011
6. Farooq S. How does stress affect your digestive health? ColoWell America. December 26, 2023. Accessed September 26, 2025. https://colowellamerica.com/how-does-stress-affect-your-digestive-health/
7. The gut-brain connection. Harvard Health Publishing. July 18, 2023. Accessed September 26, 2025. https://www.health.harvard.edu/diseases-and-conditions/the-gut-brain-connection
8. Gupta N. Stress-related stomach pain: when to see a doctor. UChicago Medicine. January 4, 2024. Accessed September 26, 2025. https://www.uchicagomedicine.org/forefront/gastrointestinal-articles/stress-stomach-pain-when-to-see-a-doctor