If you have IBS and anxiety, you have probably heard at least one of these:
“Your stomach problems are caused by anxiety. You need to learn to relax.”
Or alternatively, from a different doctor on a different day: “Your anxiety is caused by your gut issues. Once we get your digestion sorted out, you’ll feel better.”
Both of these statements contain truth. Both of them are also incomplete. And the reason this question matters so much — which came first, which is causing which — is that the answer shapes everything about how you approach getting better.
So let’s actually answer it.
The Honest Answer: Both Are True, at the Same Time
Your gut and your brain are not two separate systems that occasionally send messages to each other. They are one integrated system with constant, real-time, bidirectional communication happening every moment of every day.
The nerve connecting them — the vagus nerve — carries signals in both directions. And importantly, roughly 80 to 90 percent of those signals travel upward, from gut to brain, not the other way around (Rao & Gershon, 2016). Your gut is continuously influencing your brain state: your mood, your threat perception, your anxiety levels.
What this means is that a dysregulated gut can genuinely cause anxiety. Not metaphorically. Not as a side effect. As a direct biological output of signals traveling from your enteric nervous system up through the vagus nerve to the parts of your brain that process danger.
And at the same time, anxiety genuinely causes gut dysfunction. Stress hormones disrupt digestion, speed up or slow down motility, lower the threshold for pain, and keep the gut in a state of heightened alert (Rao & Gershon, 2016).
So you are not imagining either direction. They are both real. They are happening simultaneously. And they are feeding each other in a loop that can feel very hard to escape.
Why the “Which Came First” Question Actually Matters
Here is why I bring this up, though: the framing you receive from the people around you shapes how you feel about yourself.
When a doctor says “it’s just anxiety,” the implied message is that your gut symptoms are not really physical — that they are a product of your mind, and if you just got your emotions under control, your body would follow. This framing is not only incomplete, it is genuinely harmful. It places the blame on you. It suggests the solution is willpower or attitude. And it often leads to years of people doubting their own physical experience.
When someone says “it’s just IBS, nothing to do with anxiety,” the implication is the opposite — that the gut is a plumbing problem, and the psychological piece is either irrelevant or a separate issue to be handled elsewhere. This also leaves people without the full picture.
The truth — that your gut and brain are one system, and that dysregulation in one genuinely produces dysregulation in the other — is actually empowering. Because it means that treating either end of the loop creates change. You do not have to resolve your anxiety completely before your gut can calm down. And you do not have to wait for your gut to be perfectly managed before you can address the nervous system piece. Intervening anywhere in the cycle creates ripple effects throughout.
What the Loop Actually Looks Like
For most people with IBS and anxiety, it goes something like this — though you can enter the loop at any point:
Something happens in your gut. Maybe a sensation, maybe cramping, maybe just a vague sense of unease. Your brain — already on high alert because of previous bad experiences with your gut — immediately interprets this as a potential emergency. Anxiety fires. Your body releases stress hormones. Those stress hormones go right back to your gut and amplify whatever was happening there. Now the symptoms are worse. The anxiety gets worse. You start thinking about whether you are going to be okay, whether you need to cancel your plans, whether this is going to be a bad day. That thinking — that catastrophizing — is not weakness, it is a completely understandable response to real and repeated suffering. But it also keeps the loop running.
Over time, the brain starts anticipating the loop before it even begins. You wake up and before anything has happened, the anxiety is already there, because your nervous system has learned that mornings are dangerous, that certain situations are dangerous, that your gut is unpredictable and therefore a constant threat.
This is not a character flaw. It is a nervous system that has done exactly what nervous systems do: learned from experience and tried to protect you.
The problem is that the protection mechanism has become the problem itself.
What Changes When You Understand This
When you understand that the anxiety and the gut symptoms are part of the same loop, a few things shift.
First, you stop fighting yourself. The anxiety about your gut is not a sign that you are “too stressed” or “not resilient enough.” It is a logical output of a system that has been trained to be vigilant. That is different. You are not broken. You are responsive.
Second, you start to see that treatment does not have to be linear. You do not have to fix the gut first and then address the anxiety, or vice versa. Approaches that work on the gut-brain connection — like gut-directed CBT and gut-directed hypnotherapy — address the loop directly, targeting both ends simultaneously (Lackner et al., 2018; Adler et al., 2025). This is why people who use these approaches often report improvements in both their physical symptoms and their anxiety, not one or the other.
Third, you become less afraid of the anxiety itself. One of the most exhausting parts of the anxiety-IBS loop is the anxiety about the anxiety — the fear that feeling anxious means the gut symptoms are coming. When you understand that anxiety is not automatically a prediction, just a signal, you start to develop a different relationship with it. And as that relationship changes, the loop begins to lose its grip.
A Note on “It’s Just Anxiety”
I want to come back to this phrase, because it does real damage.
When you are told “it’s just anxiety,” the implicit message is minimization. But anxiety is not a small thing. Anxiety that is running through a gut-brain feedback loop, creating real physical pain and urgency, limiting your life and your choices — that is not “just” anything.
What I would offer instead is this framing: your anxiety and your gut symptoms are connected, and that connection is not a weakness or a character flaw. It is a biology. And biology is something we can work with.
You are not too anxious. You are not too emotional. You are not catastrophizing for no reason. You are a person whose nervous system has been under significant strain, and who deserves care that honors the full picture of what that means.
About the author
Susan Liddy, MAMFT is a GI Psychotherapist and doctoral candidate in Integrative Health, specializing in nervous system-informed care for IBS and disorders of gut-brain interaction. Georgia residents are welcome to schedule a free consultation at www.susanliddy.com.
This article is for educational purposes and does not constitute medical or psychological advice. Please consult your healthcare providers for individual guidance.
References
Adler, E. C., Levine, E. H., Ibarra, A. N., Boparai, E. S., Hung, Y.-Y., McCrary, Q. D., & Lee, J. K. (2025). Gut-directed hypnotherapy for irritable bowel syndrome: A systematic review and meta-analysis. Neurogastroenterology & Motility, 37(4), e70037. https://doi.org/10.1111/nmo.70037
Lackner, J. M., Jaccard, J., Keefer, L., Brenner, D. M., Firth, R. S., Gudleski, G. D., Hamilton, F. A., Katz, L. A., Krasner, S. S., Ma, C.-X., Radziwon, C. D., & Sitrin, M. D. (2018). Improvement in gastrointestinal symptoms after cognitive behavior therapy for refractory irritable bowel syndrome. Gastroenterology, 155(1), 47–57. https://doi.org/10.1053/j.gastro.2018.03.063
Rao, M., & Gershon, M. D. (2016). The bowel and beyond: The enteric nervous system in neurological disorders. Nature Reviews Gastroenterology & Hepatology, 13(9), 517–528. https://doi.org/10.1038/nrgastro.2016.107
