What is the appropriate first‑line management for an adult with uncomplicated abdominal bloating and no red‑flag symptoms?

First-Line Management of Uncomplicated Abdominal Bloating

For an adult with uncomplicated abdominal bloating and no red-flag symptoms, begin with a 2-week empirical dietary restriction of lactose and fructose, as carbohydrate intolerance is the most common identifiable cause, affecting 51-60% of patients with bloating. 1

Initial Diagnostic Approach

Rule Out Constipation First

• Assess whether constipation is present using Rome IV criteria for IBS-C or chronic constipation. 1 If constipation coexists, treat it with osmotic laxatives or secretagogues (linaclotide, lubiprostone, plecanatide) before attributing symptoms solely to bloating. 1, 2
• Ask specifically about straining with defecation, incomplete evacuation, and stool consistency using the Bristol Stool Scale. 3
• If pelvic floor dyssynergia is suspected (straining even with soft stool, need for digital disimpaction), obtain anorectal manometry. 1, 3

Identify Food Intolerances

• The simplest and most cost-effective diagnostic approach is a 2-week dietary elimination of lactose and fructose. 1 Resolution of symptoms during this trial is a positive predictor of carbohydrate intolerance.
• Reserve hydrogen-based breath testing (glucose or lactulose) only for patients who fail dietary restriction or when SIBO risk factors are present. 1
• Screen for celiac disease with tissue transglutaminase IgA plus total IgA measurement, especially if bloating is accompanied by diarrhea, weight loss, or anemia. 1, 4

Exclude Red-Flag Symptoms

• Obtain complete blood count, comprehensive metabolic panel, and C-reactive protein to exclude inflammatory conditions. 1, 3
• Red flags requiring urgent evaluation include: unintentional weight loss >10%, GI bleeding, persistent vomiting, family history of inflammatory bowel disease or colorectal cancer, and age >50 without recent colonoscopy. 1, 3
• In patients over 50 years, schedule colonoscopy to exclude colorectal malignancy even if other workup is negative. 5

First-Line Treatment for Functional Bloating

Dietary Modification

• Refer to a gastroenterology dietitian for a low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet trial. 1, 5 This addresses the osmotic effects and fermentation of poorly absorbed carbohydrates that trigger bloating in patients with visceral hypersensitivity.
• Do not recommend probiotics routinely, as evidence shows no benefit for bloating or distention. 5

Pharmacologic Options When Diet Alone Is Insufficient

For bloating with constipation (IBS-C):

• Secretagogues are first-line: linaclotide, plecanatide, or lubiprostone reduce bloating with a number-needed-to-treat of 8. 2 A meta-analysis of 13 randomized trials shows all three improve bloating with no clinically meaningful differences among them. 2
• Tenapanor (sodium-hydrogen exchanger-3 inhibitor) is an additional option. 2

For bloating with visceral hypersensitivity or severe symptoms:

• Central neuromodulators (tricyclic antidepressants or SSRIs) reduce bloating by modulating visceral sensation and attenuating abnormal diaphragm-abdominal wall dyssynergia. 2 These are especially effective for meal-related distention. 2
• Prucalopride (5-HT₄ agonist) yields moderate-to-severe improvement in bloating with NNT of 8, primarily indicated when constipation or gastroparesis coexists. 2

Common Pitfalls to Avoid

• Do not pursue extensive testing (CT imaging, colonoscopy, breath tests) in young patients without alarm features before trying dietary modification. 1 The 2023 AGA guideline emphasizes that a 2-week dietary trial is more economical and diagnostically useful than immediate testing. 1
• Do not label bloating as functional in elderly patients (especially >80 years) without first excluding malignancy and obstruction through imaging and endoscopy. 5 Colorectal cancer accounts for ~60% of large-bowel obstructions in this population. 5
• Discontinue medications that impair gut motility before initiating treatment: opioids, anticholinergics (cyclizine), calcium-channel blockers, and antidepressants with anticholinergic properties can cause or worsen bloating. 2
• Exclude mechanical obstruction with contrast-enhanced CT before starting any prokinetic agent, as prokinetics worsen pain in true obstruction. 2

When to Escalate Care

• If symptoms persist despite dietary modification and first-line pharmacotherapy, consider SIBO testing with breath tests or small bowel aspirates. 1
• Refer to gastroenterology if alarm symptoms develop, if there is diagnostic uncertainty, or if symptoms worsen despite appropriate management. 1
• In patients with nausea and vomiting, rule out gastroparesis with motility studies. 1