Chronic stomach pain is overwhelmingly caused by conditions that are uncomfortable and disruptive but not dangerous. In a landmark study of 2,000 gastroenterology outpatients, nearly half had no identifiable structural disease at all, and among those functional cases, irritable bowel syndrome accounted for roughly half again.1PubMed. Organic and functional disorders in 2000 gastroenterology outpatients That said, “not dangerous” and “not miserable” are two different things, and a smaller but real subset of chronic abdominal pain does signal something that needs medical attention. Understanding the landscape helps you figure out where you probably fall and when to push for more investigation.
The Most Common Reason for Ongoing Stomach Pain
Functional gastrointestinal disorders are, by a wide margin, the most common diagnoses in gastroenterology. The term “functional” means there is no visible ulcer, tumor, or inflammation explaining the pain. That does not mean the pain is imagined. These conditions involve real, measurable abnormalities in how the gut moves, how sensitive its nerves are, how the immune system interacts with the gut lining, and how the brain processes signals from the digestive tract.2Gastroenterology. Functional Gastrointestinal Disorders: History, Pathophysiology, Clinical Features, and Rome IV The two big ones are irritable bowel syndrome and functional dyspepsia.
IBS shows up as recurring abdominal pain linked to changes in bowel habits. Some people lean toward diarrhea, some toward constipation, and some alternate between the two.3PubMed Central. New insights into irritable bowel syndrome: from pathophysiology to treatment Functional dyspepsia, on the other hand, centers on the upper abdomen. It splits into two patterns: one dominated by bloating and early fullness after eating, and another dominated by a burning or gnawing pain in the upper stomach area.4PubMed Central. Functional Dyspepsia: A Review of the Symptoms, Evaluation, and Treatment Options People with the bloating-dominant type tend to have heightened sensitivity to stomach stretching both before and after meals, while those with the pain-dominant type show reduced stomach capacity at rest.5PubMed. Fasting and postprandial gastric sensorimotor activity in functional dyspepsia: postprandial distress vs. epigastric pain syndrome The practical upshot is that what feels like “my stomach always hurts” can actually be two quite different problems depending on whether the pain ties to eating or to bowel movements.
Why the Gut Becomes Oversensitive
A concept called visceral hypersensitivity sits at the center of most chronic functional gut pain. Normally, your gut sends signals up through the spinal cord to the brain, and most of those signals never reach conscious awareness. In people with visceral hypersensitivity, the volume dial on those signals is turned up. The brain receives and amplifies input from the digestive tract that would be filtered out in someone without the condition.6PubMed Central. The Importance of Visceral Hypersensitivity in Irritable Bowel Syndrome-Plant Metabolites in IBS Treatment Brain imaging studies confirm that people with functional gut disorders show altered activity in the cortical and subcortical regions responsible for processing pain.7British Medical Bulletin. Visceral pain hypersensitivity in functional gastrointestinal disorders
This is not a character flaw or a sign that someone is “too sensitive.” It is a measurable neurological phenomenon involving specific ion channels, neurotransmitter receptors, and changes in both the peripheral nerves of the gut and the central processing pathways in the brain. Chronic stress makes it worse by altering gut motility, increasing intestinal permeability, and modifying the central pain circuits themselves.8PubMed Central. Stress and the Microbiota-Gut-Brain Axis in Visceral Pain: Relevance to Irritable Bowel Syndrome This is why people often notice their stomach problems flare during stressful periods. The stress response involves specific receptor systems that simultaneously speed up the colon and slow down the stomach, which can produce both diarrhea and upper abdominal discomfort at the same time.9PubMed. Stress and the gastrointestinal tract
Organic Causes That Do Need Attention
While functional disorders dominate the landscape, the other half of that 2,000-patient study did have structural diseases, and peptic ulcers, esophagitis, and inflammatory bowel disease accounted for roughly half of those organic diagnoses.1PubMed. Organic and functional disorders in 2000 gastroenterology outpatients These are the conditions where delayed diagnosis carries real consequences.
Helicobacter pylori infection is one of the more common treatable causes. This bacterium colonizes the stomach lining, causes inflammation, and in some people progresses to ulcers. Microbiological, serological, and epidemiological evidence confirms it plays an important role in both gastritis and peptic ulcer disease, and antibiotic therapy directed against it can resolve symptoms.10Advances in Pediatrics. Helicobacter pylori, Gastritis, and Ulcers in Pediatrics The tricky part is that H. pylori doesn’t always explain symptoms. One endoscopy study found that neither the concentration of the bacteria nor the severity of gastritis correlated with the patients’ specific symptoms like nausea, bloating, or pain.11PubMed. Symptoms, gastritis, and Helicobacter pylori in patients referred for endoscopy And long-term follow-up research has shown that the prognosis for dyspepsia without ulcers is generally good regardless of whether H. pylori is present.12PubMed Central. Long-term follow up of patients with gastritis associated with Helicobacter pylori infection So finding the bacteria doesn’t automatically mean it’s causing your pain, and not finding it doesn’t rule out a structural problem. Testing is still worthwhile because when H. pylori is the culprit, treatment can be curative.
Inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis, is a more serious concern. These conditions involve chronic inflammation of the intestinal wall and can cause long-term damage if untreated. Complicating matters, Crohn’s disease and IBS share symptoms like abdominal pain and diarrhea, which can delay correct diagnosis. IBS is an important consideration in the differential diagnosis of Crohn’s, and roughly one in three Crohn’s patients in remission also has overlapping IBS symptoms running in parallel.13PubMed Central. Crohn’s disease, irritable bowel syndrome, and chronic fatigue: the importance of communication and symptom management Central sensitization, the same amplified pain processing seen in IBS, also shows up in inflammatory bowel disease and is associated with how severe the gut symptoms feel.14PubMed. Central sensitization and severity of gastrointestinal symptoms in irritable bowel syndrome, chronic pain syndromes, and inflammatory bowel disease
Medications That Can Cause Chronic Stomach Pain
If your stomach started hurting around the time you began taking a new medication, that is worth investigating before assuming you have a gut disorder. Nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen are among the most common offenders. They work by blocking enzymes involved in inflammation, but those same enzymes produce protective compounds in the stomach lining. Blocking them reduces the stomach’s ability to defend itself against its own acid.15PubMed Central. Effects of Non-steroidal Anti-inflammatory Drugs (NSAIDs) and Gastroprotective NSAIDs on the Gastrointestinal Tract: A Narrative Review With chronic use, this can progress from mild irritation to full-blown ulcers.16PubMed. Prostaglandins, NSAIDs, and gastric mucosal protection: why doesn’t the stomach digest itself? The fix is often straightforward: switch pain relievers, add a stomach-protecting medication, or stop the drug if possible.
Opioid painkillers present a different and more paradoxical problem. Long-term use can actually increase abdominal pain through a phenomenon where the nervous system ramps up its pain sensitivity in response to the drug. The mechanisms behind this enhanced pain perception include activation of anti-analgesic pathways and changes in how the brainstem processes pain signals.17PubMed Central. The narcotic bowel syndrome: clinical features, pathophysiology, and management Taking more of the painkiller to address the worsening stomach pain creates a vicious cycle. If you are on chronic opioids and your abdominal pain keeps getting worse despite dose increases, this is a pattern your doctor needs to know about.
Food Intolerances and the Problem of Self-Diagnosis
Many people with chronic stomach pain become convinced that a specific food or food group is the problem. Sometimes they are right. But the path from suspicion to correct identification is messier than it looks. Non-celiac gluten sensitivity, for instance, is a real condition characterized by abdominal pain, fatigue, and sometimes symptoms outside the gut like headache and joint pain.18PubMed Central. Extra-intestinal manifestations of non-celiac gluten sensitivity: An expanding paradigm The trouble is that there are no reliable diagnostic markers for it. Diagnosis depends on whether symptoms improve on a gluten-free diet and return when gluten is reintroduced, and the placebo effect plays a meaningful role in that process.19PubMed Central. Non-celiac gluten sensitivity: Time for sifting the grain The patients themselves are a heterogeneous group with a lot of individual variation, though abdominal pain and fatigue are the two most consistently reported symptoms.20Gastroenterología y Hepatología (English Edition). Non-celiac gluten sensitivity: Clinical presentation, etiology and differential diagnosis
A more structured dietary approach that has gained strong evidence is restricting FODMAPs, which are certain fermentable carbohydrates found in a wide range of foods including wheat, onions, garlic, beans, and some fruits. Reducing FODMAP intake lowers the amount of water drawn into the intestine and the amount of gas produced by fermentation in the colon. Studies have consistently shown that up to 86% of IBS patients experience improvement in overall symptoms including pain, bloating, and altered bowel habits when following this diet.21PubMed Central. Efficacy of the low FODMAP diet for treating irritable bowel syndrome: the evidence to date The diet is meant to be done in phases under guidance, not as a permanent blanket restriction, since many high-FODMAP foods are nutritionally valuable and people’s tolerances vary widely.22PubMed Central. Low FODMAP Diet: Evidence, Doubts, and Hopes
Ultra-Processed Foods and the Gut Barrier
Beyond specific intolerances, there is growing concern that the cumulative effect of modern processed food may be contributing to chronic gut inflammation independent of any single ingredient. Researchers have hypothesized that emulsifiers commonly added to processed foods may increase gut permeability by damaging the mucus layer that protects the intestinal lining. This disruption allows bacterial components to cross the gut barrier, triggering a state of low-grade chronic inflammation.23PubMed Central. Food Emulsifiers and Metabolic Syndrome: The Role of the Gut Microbiota This research is still in its early stages, and it would be premature to blame processed food for any individual person’s stomach pain. But it adds context for why some people find their symptoms improve broadly when they shift toward less processed diets, even without identifying a single trigger food.
When the Problem Might Not Be Your Gut at All
Chronic lower abdominal pain in women deserves a special mention because conditions like endometriosis can mimic or coexist with IBS. The two share symptoms of pain and sometimes diarrhea, and the overlap leads to misdiagnosis, unnecessary testing, and delays in proper treatment going in both directions.24PubMed. Endometriosis and irritable bowel syndrome: a systematic review and meta-analysis If your abdominal pain has any cyclical pattern tied to your menstrual cycle, or if standard IBS treatments aren’t helping, raising the possibility of endometriosis with your doctor is worth doing. The average delay in endometriosis diagnosis is measured in years, and chronic gut-like pain is one of the reasons why.
Sleep quality also feeds into chronic gut pain in a way people don’t always connect. Sleep deprivation can lower the threshold at which gut sensations register as painful, and poor sleep has been implicated as a contributing factor in chronic pain amplification syndromes.25PubMed. Sleep disturbances in clinic patients with functional bowel disorders If you have chronic stomach pain and you are also sleeping badly, addressing the sleep may directly lower the pain even if nothing about your gut changes.
When to Push for More Testing
Doctors sometimes get criticized for not ordering enough tests, but the evidence on imaging for chronic abdominal pain suggests the opposite problem. Diagnostic imaging is often not indicated for chronic abdominal pain. Undifferentiated stomach pain is rarely a reason for a CT scan, and CT scanning tends to be overused even when imaging is called for.26PubMed Central. Imaging for chronic abdominal pain in adults Repeated scans after an initial negative scan are particularly low-yield. In one study of patients who had multiple CT scans for nontraumatic abdominal pain, the first scan found something meaningful about 23% of the time, but by the second scan that rate dropped to around 8%, and by the third and beyond it was below 5%.27PubMed. Utility of repeated abdominal CT scans after prior negative CT scans in patients presenting to ER with nontraumatic abdominal pain
That said, certain symptoms should prompt you to insist on investigation rather than accepting a functional diagnosis. These are the features that make doctors sit up and take notice:
- Unintentional weight loss: losing weight without trying, especially more than a few pounds over weeks.
- Blood in the stool: visible blood or black, tarry stools that suggest bleeding higher in the digestive tract.
- New onset after age 50: first-time chronic abdominal pain starting in middle age or later raises concern for things that become more common with age.
- Fever: recurring or persistent fever alongside abdominal pain suggests infection or inflammation.
- Nighttime awakening: functional disorders rarely wake people from sleep. Pain that consistently wakes you up deserves workup.
- Progressive worsening: functional pain fluctuates. Pain that only ever gets worse is a different pattern.
- Family history: close relatives with inflammatory bowel disease, celiac disease, or gastrointestinal cancers lower the bar for testing.
None of these features automatically means something serious is happening, but each one shifts the probability enough that a doctor should be investigating rather than reassuring.
Treatments That Actually Help Functional Pain
If your chronic stomach pain is functional, the goal shifts from finding and fixing a broken thing to calming an overactive system. The low-FODMAP dietary approach mentioned earlier is one pillar. Medications are another. Low-dose tricyclic antidepressants have shown clear benefit for IBS. In a well-designed trial, patients taking a low dose of amitriptyline saw substantially greater improvement in IBS symptom scores compared to placebo, and were roughly twice as likely to report meaningful relief of their overall symptoms.28American Journal of Gastroenterology. Low-dose Tricyclic Antidepressants for Irritable Bowel Syndrome: Definitive Evidence of Benefit from ATLANTIS The doses used for gut pain are typically much lower than those used for depression, and the benefit comes from the drug’s effect on nerve signaling in the gut, not from treating a mood disorder. Evidence in children and adolescents with functional abdominal pain is less consistent, so the risk-benefit calculation differs by age.29PubMed Central. Focus on the use of antidepressants to treat pediatric functional abdominal pain: current perspectives
Gut-directed hypnotherapy is one of the more surprising evidence-based options. It involves guided sessions where a trained therapist uses specific suggestions and imagery aimed at changing how the brain processes gut signals. Research suggests this approach may drive genuine neuroplastic changes, essentially retraining the brain-gut connection and restoring more normal processing of sensations that had been registering as painful.30PubMed Central. Gut‐focused hypnotherapy for Functional Gastrointestinal Disorders: Evidence‐base, practical aspects, and the Manchester Protocol It is not a fringe treatment. Major gastroenterology guidelines include it as a recommended option for functional gut disorders that haven’t responded to first-line approaches.
Small Intestinal Bacterial Overgrowth as a Contested Diagnosis
You may have encountered SIBO (small intestinal bacterial overgrowth) as a proposed explanation for chronic gut symptoms, especially in integrative or functional medicine circles. The idea is that bacteria that normally live in the large intestine migrate upward into the small intestine, where they ferment food prematurely and produce gas, bloating, and pain. Real SIBO does exist and can be treated with antibiotics, as case reports have confirmed with resolution of symptoms after targeted therapy.31PubMed Central. Difficulties in diagnosing a pediatric patient with small intestinal bacterial overgrowth
The problem is that the main testing method, the breath test, seems to pick up abnormalities in an enormous number of people. In one controlled study of children with chronic abdominal pain, over 90% in both the treatment group and the placebo group had abnormal breath tests suggesting SIBO. Antibiotic treatment successfully normalized the breath test in only 20% of those treated, and there was no significant difference in symptom improvement between the antibiotic and placebo groups.32PubMed. Double-blind, placebo-controlled antibiotic treatment study of small intestinal bacterial overgrowth in children with chronic abdominal pain This raises real questions about whether the breath test is accurately identifying the problem and whether the bacterial overgrowth is actually causing the symptoms in most cases. Be cautious about repeated courses of antibiotics for SIBO if you are not seeing clear improvement.