That knot in your stomach when you’re anxious? It’s real, it’s physical, and you’re far from the only one. Anxiety bloating and the “nervous stomach” are some of the most common — and most dismissed — ways that stress shows up in the body. Let’s name what’s happening, gently and clearly.
Why anxiety lands in your gut
When you’re anxious, your body shifts into fight-or-flight. Digestion isn’t a priority in that state, so motility changes, you may swallow more air, and you become more sensitive to normal gut sensations. Add it up and you get bloating, cramping, urgency, or that hollow “butterflies” feeling. This is the gut-brain axis in action.
Why you get gassy when you’re nervous
Two things are usually going on. The first is air. Everyone swallows a little air when they eat and drink, and swallowing more air can mean more gas (NIDDK). Anxiety may add to it: in a 2023 study of 161 adults with reflux and indigestion symptoms, people with moderate or severe anxiety swallowed air significantly more often than people with mild anxiety (Ribolsi et al., 2023).
The second is sensitivity. When the brain and gut aren’t working together smoothly, you can feel more bloating or belly pain, and gas can move through your intestines differently (NIDDK). The rest of your gas is made by your gut bacteria. Carbohydrates you don’t digest pass to the large intestine, where bacteria break them down and make gas along the way. That part is normal.
IBS, bloating and the gut-brain axis
Irritable bowel syndrome (IBS) is a group of symptoms that show up together: repeated belly pain plus changes in bowel movements, which may be diarrhea, constipation or both. About 12 percent of people in the US have it. Doctors now call IBS and similar functional GI problems disorders of gut-brain interaction, because they relate to how the brain and gut work together (NIDDK).
The Rome IV diagnostic criteria describe several changes that often show up together in these conditions: altered gut movement, a more sensitive gut (visceral hypersensitivity), altered immune function, an altered gut microbiota, and changes in how the brain processes gut signals (Drossman, 2016). A 2017 review explains how stress affects gut permeability, movement, microbiota, sensitivity and secretion, and says anxiety plays a major role in gut function through the brain-gut axis (Pellissier & Bonaz, 2017).
Talk with your doctor if gas symptoms bother you, change suddenly, or come with belly pain, constipation, diarrhea or weight loss (NIDDK).
Where your gut bacteria come in
Your gut microbes are part of the same conversation. A major 2019 review in Physiological Reviews describes the microbiota and the brain communicating through the immune system, tryptophan metabolism, the vagus nerve and the enteric nervous system, using microbial products such as short-chain fatty acids. The same review notes that stress can significantly affect this microbiota-gut-brain axis at every stage of life (Cryan et al., 2019).
Where Flore fits
That’s why Flore starts with your gut data, not a guess. A CLIA-certified partner lab sequences your sample. Flore reads the results and builds a probiotic and prebiotic formula around what your own microbiome shows. Flore has analyzed 23,000+ microbiome reports and built 40,000+ personalized formulations. If you have an IBS diagnosis, keep your provider in the loop. A Flore formula is a supplement that supports your gut. It isn’t a treatment for IBS, anxiety or any condition.
Start here: Test-to-Treat: a microbiome test plus a formula built from your results. Or read what neurobiome testing is.
Anxiety and stomach problems feed each other
It can become a loop: anxiety upsets your gut, and an upset gut makes you more anxious. Recognizing the loop is the first step to gently interrupting it — you’re not failing, your nervous system is just doing its job a little too well.
Gentle ways to ease both
Because the gut and brain share a line, calming one tends to soothe the other: slow, long exhales; steady sleep; daily movement; easing back on caffeine; and warmth and rest when a flare hits. Supporting your gut microbiome with fiber and fermented foods is a reasonable longer-term layer. If your stomach problems are frequent, severe, or come with warning signs (blood, weight loss, persistent pain), please see a provider to rule out other causes.
About Flore. Flore makes personalized probiotic capsules and powders (never liquid) matched to your own gut data. Flore doesn’t run the lab test itself — that’s done by CLIA-certified labs — and then formulates around your results, rather than handing you a one-size shelf product. Flore Inc. acquired Sun Genomics in 2026. Flore is a wellness product and is not a treatment, cure, or substitute for care from a licensed provider.
Not every gut problem shows up in your gut.
If stress and your stomach seem to move together, you’re not imagining it — and you don’t have to figure it out alone. Take our short, gentle gut-brain check-in and we’ll point you to a kind next step. No medical quiz, no pressure.
Frequently asked questions
Why do I get bloated when I’m anxious?
Stress and anxiety activate your body’s fight-or-flight response, which can slow or disrupt digestion, change gut motility, and increase your awareness of normal gut sensations. The result can be bloating, a knotted “nervous stomach,” or irregularity. It’s a real, physical effect of the gut-brain connection — not “all in your head.”
What is a nervous stomach?
A “nervous stomach” is a common, non-medical way of describing digestive symptoms — butterflies, nausea, cramping, urgency, or bloating — that flare with stress or anxiety. It reflects the close communication between your brain and your gut.
How do I calm anxiety and stomach problems together?
Because they’re linked, approaches that calm your nervous system — slow breathing, regular sleep, movement, limiting caffeine — often help both. Supporting gut health with fiber and fermented foods is reasonable too. If symptoms are frequent or severe, see a health-care provider to rule out other causes.
Why do I get gassy when I’m nervous?
Swallowing more air can mean more gas, and one 2023 study found people with moderate or severe anxiety swallowed air more often than people with mild anxiety. Stress can also make your gut more sensitive, so normal gas feels like more. If gas bothers you, changes suddenly, or comes with pain, bowel changes or weight loss, talk with your doctor.
Is IBS connected to the gut-brain axis?
Yes. Doctors now call IBS a disorder of gut-brain interaction, meaning it relates to how the brain and gut work together. Research describes stress affecting gut movement, sensitivity and the gut microbiota. IBS needs a diagnosis from a clinician. Probiotics, including Flore, are not a treatment for it.
This article is for general wellness information and is not medical advice. Probiotics are not a treatment or cure for anxiety, depression, or any condition. If anxiety is affecting your daily life, please reach out to a licensed health-care provider — and if you’re in crisis, call or text 988 (US) for the Suicide & Crisis Lifeline.
Sources
- NIDDK. Symptoms & Causes of Gas in the Digestive Tract. niddk.nih.gov
- NIDDK. Definition & Facts for Irritable Bowel Syndrome. niddk.nih.gov
- Ribolsi M, et al. Anxiety correlates with excessive air swallowing and PPI refractoriness in patients with concomitant symptoms of GERD and functional dyspepsia. Neurogastroenterol Motil. 2023;35(7):e14550. doi:10.1111/nmo.14550 (PubMed)
- Drossman DA. Functional Gastrointestinal Disorders: History, Pathophysiology, Clinical Features and Rome IV. Gastroenterology. 2016. doi:10.1053/j.gastro.2016.02.032 (PubMed)
- Pellissier S, Bonaz B. The Place of Stress and Emotions in the Irritable Bowel Syndrome. Vitam Horm. 2017;103:327-354. doi:10.1016/bs.vh.2016.09.005 (PubMed)
- Cryan JF, et al. The Microbiota-Gut-Brain Axis. Physiol Rev. 2019;99(4):1877-2013. doi:10.1152/physrev.00018.2018 (PubMed)
Related: some anxiety-like physical symptoms trace back to histamine — read can histamine cause anxiety? the gut–histamine link, explained.
Not sure where to start with your gut?
Ask the Flore Microbiome Concierge — a guided, personalized walkthrough of testing, your results, and a formula matched to your goals.
Talk to the Concierge →Explore the gut-brain axis in depth →
Related reading: Does gut health affect cortisol? — how the gut microbiome helps regulate the HPA axis behind your main stress hormone.