Why Is My Stomach Always Bloated? Causes of Persistent Daily Bloating

What does it actually mean to be bloated all the time?

Bloating is a feeling of pressure, fullness, or tightness in the abdomen — often with visible swelling. It happens when there is excess gas in the gut, when the gut moves slowly, or when the gut is unusually sensitive to normal amounts of gas and contents. Occasional bloating after a big meal is common. Persistent bloating — present most days, interfering with daily life — is a different story and usually has a diagnosable cause 1Ref 1Moshiree B, Drossman D, Shaukat A (2023).AGA Clinical Practice Update on Evaluation and Management of Belching, Abdominal Bloating, and Distention: Expert Review.Mechanisms of bloating including gas, slow motility, visceral hypersensitivity, FODMAP fermentation, and SIBO; approach to evaluation.

Eating too quickly and swallowing air (aerophagia) is a contributing factor, as is eating large meals at one sitting. Constipation is one of the most underappreciated causes: stool backing up in the colon displaces and traps gas, creating that tight, full feeling throughout the day. Certain foods — particularly those high in FODMAPs (fermentable carbohydrates like onions, garlic, apples, beans, and wheat) — cause excess gas production in many people by feeding gut bacteria 1Ref 1Moshiree B, Drossman D, Shaukat A (2023).AGA Clinical Practice Update on Evaluation and Management of Belching, Abdominal Bloating, and Distention: Expert Review.Mechanisms of bloating including gas, slow motility, visceral hypersensitivity, FODMAP fermentation, and SIBO; approach to evaluation.

Which gut conditions most commonly cause chronic bloating?

Irritable bowel syndrome (IBS) is one of the most common causes. Bloating and abdominal distension are among its most bothersome symptoms. People with IBS often have a gut that is hypersensitive (visceral hypersensitivity), perceiving normal amounts of gas as painful or excessive 2Ref 2Lacy BE, Pimentel M, Brenner DM, Chey WD, Keefer LA, Long MD, Moshiree B (2021).ACG Clinical Guideline: Management of Irritable Bowel Syndrome.IBS as a common cause of chronic bloating; visceral hypersensitivity; symptom patterns including relation to bowel habits and stress.

Small intestinal bacterial overgrowth (SIBO) occurs when bacteria that normally live in the large intestine grow in the small intestine, where they rapidly ferment carbohydrates and produce large amounts of gas. Bloating from SIBO is often worst after any meal containing carbohydrates — not just high-FODMAP ones 1Ref 1Moshiree B, Drossman D, Shaukat A (2023).AGA Clinical Practice Update on Evaluation and Management of Belching, Abdominal Bloating, and Distention: Expert Review.Mechanisms of bloating including gas, slow motility, visceral hypersensitivity, FODMAP fermentation, and SIBO; approach to evaluation.

Lactose intolerance and fructose malabsorption are specific food intolerances that cause gas and bloating after consuming their respective sugars. Celiac disease — an immune response to gluten — causes bloating as part of broader gut inflammation and malabsorption 3Ref 3Rubio-Tapia A, Hill ID, Semrad C, Kelly CP, Greer KB, Limketkai BN, Lebwohl B (2023).American College of Gastroenterology Guidelines Update: Diagnosis and Management of Celiac Disease.Celiac disease as a cause of bloating and malabsorption; tTG-IgA serology requirement for active gluten exposure.

Chronic constipation is frequently the overlooked driver. When stool moves slowly through the colon, trapped gas has nowhere to go 4Ref 4Chang L, Chey WD, Imdad A, et al. (2023).American Gastroenterological Association-American College of Gastroenterology Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation.Constipation as an underappreciated driver of bloating; evaluation and management approach.

Less common but important causes worth discussing with a clinician

In women, endometriosis and ovarian cysts can cause cyclic or persistent bloating that feels like a gut problem but originates in the reproductive system. Hypothyroidism (underactive thyroid) slows gut motility and can cause constipation and bloating 5Ref 5Jonklaas J, Bianco AC, Bauer AJ, et al. (2014).Guidelines for the Treatment of Hypothyroidism: Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement.Hypothyroidism as a cause of slow gut motility, constipation, and bloating; TSH as a screening test.

Ascites — fluid accumulation in the abdominal cavity — causes actual enlargement of the abdomen, often mistaken for gas-bloating, and is associated with liver disease, heart failure, or certain cancers. Gastroparesis (slow stomach emptying) can cause persistent upper bloating and nausea 6Ref 6Camilleri M, Kuo B, Nguyen L, Vaughn VM, Petrey J, Greer K, Yadlapati R, Abell TL (2022).ACG Clinical Guideline: Gastroparesis.Gastroparesis and ascites as less common but important structural causes of persistent bloating requiring imaging evaluation.

For persistent new bloating in anyone over 50, a clinician should ensure colorectal cancer or ovarian pathology is not contributing.

What patterns help identify the cause?

Paying attention to timing and triggers is genuinely useful before a clinician visit:

• Bloating tied to specific foods (dairy, wheat, fruit, high-FODMAP foods) — points toward intolerance or celiac disease.
• Bloating worse after virtually any carbohydrate — raises concern for SIBO.
• Bloating worst by end of day, with hard or infrequent stools — suggests constipation as the driver.
• Bloating that fluctuates with bowel habits and stress — fits the IBS pattern 2Ref 2Lacy BE, Pimentel M, Brenner DM, Chey WD, Keefer LA, Long MD, Moshiree B (2021).ACG Clinical Guideline: Management of Irritable Bowel Syndrome.IBS as a common cause of chronic bloating; visceral hypersensitivity; symptom patterns including relation to bowel habits and stress.
• Bloating that doesn't vary with meals and the abdomen appears visibly larger — warrants prompt evaluation for ascites or structural causes.

A two-week food-and-symptom diary is one of the most practical tools you can bring to a clinician visit. Note what you ate, when bloating was worst, and how your bowels were behaving.

What might a clinician test for?

Evaluation is tailored to the clinical picture, but commonly considered tests include:

• Celiac serology (tTG-IgA): Celiac disease must be ruled out before any gluten reduction, since gluten must be in the diet for the test to be accurate 3Ref 3Rubio-Tapia A, Hill ID, Semrad C, Kelly CP, Greer KB, Limketkai BN, Lebwohl B (2023).American College of Gastroenterology Guidelines Update: Diagnosis and Management of Celiac Disease.Celiac disease as a cause of bloating and malabsorption; tTG-IgA serology requirement for active gluten exposure.
• Hydrogen/methane breath testing: Can detect SIBO or specific carbohydrate malabsorption (lactose, fructose) as drivers of gas 1Ref 1Moshiree B, Drossman D, Shaukat A (2023).AGA Clinical Practice Update on Evaluation and Management of Belching, Abdominal Bloating, and Distention: Expert Review.Mechanisms of bloating including gas, slow motility, visceral hypersensitivity, FODMAP fermentation, and SIBO; approach to evaluation.
• Stool calprotectin: Helps distinguish functional bloating (IBS) from inflammatory bowel disease.
• Thyroid-stimulating hormone (TSH): Hypothyroidism is a simple blood test and a correctable cause of slow gut motility 5Ref 5Jonklaas J, Bianco AC, Bauer AJ, et al. (2014).Guidelines for the Treatment of Hypothyroidism: Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement.Hypothyroidism as a cause of slow gut motility, constipation, and bloating; TSH as a screening test.
• Abdominal imaging (ultrasound or CT): If ascites, ovarian mass, or other structural cause is suspected — particularly in older adults with new-onset bloating 6Ref 6Camilleri M, Kuo B, Nguyen L, Vaughn VM, Petrey J, Greer K, Yadlapati R, Abell TL (2022).ACG Clinical Guideline: Gastroparesis.Gastroparesis and ascites as less common but important structural causes of persistent bloating requiring imaging evaluation.
• Colonoscopy: Appropriate for age-based screening or if symptoms suggest a structural colonic issue 4Ref 4Chang L, Chey WD, Imdad A, et al. (2023).American Gastroenterological Association-American College of Gastroenterology Clinical Practice Guideline: Pharmacological Management of Chronic Idiopathic Constipation.Constipation as an underappreciated driver of bloating; evaluation and management approach.