I have chronic abdominal pain and a history of ulcer disease; after a frozen coffee drink I experienced an 8‑hour episode of severe cramping. My lactose allergy test was negative and I am on acid‑reflux medication (proton pump inhibitor). Could this be lactose intolerance or a reaction to another ingredient, and what evaluation and management should I pursue?

Evaluation and Management of Post-Coffee Abdominal Cramping with Negative Lactose Testing

Given your negative lactose allergy test and the specific trigger of a frozen coffee drink, this is most likely fructose intolerance or another FODMAP sensitivity rather than lactose intolerance, especially since you are already on acid reflux medication with good symptom control. 1

Why This Is Probably Not Lactose Intolerance

• Your lactose test was negative, and importantly, at least 50% of patients with presumed lactose intolerance actually have broader intolerance to FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols), not lactose specifically 1
• Patient self-reports of lactose intolerance correlate poorly with objective evidence—you cannot rely on your suspicion alone 1
• Only patients consuming more than 280 ml (0.5 pint) of milk or dairy equivalent daily typically need lactose intervention, as those consuming less generally tolerate moderate quantities even if lactose intolerant 1
• The fact that a frozen coffee drink (likely containing high-fructose corn syrup, sugar alcohols, or other sweeteners) triggered your symptoms more than solid dairy foods strongly suggests a different culprit 2

Most Likely Culprits in Your Frozen Coffee Drink

Fructose intolerance is seen in approximately 60% of patients with digestive disorders and causes symptoms identical to what you experienced 2:

• High-fructose corn syrup in sweetened frozen coffee drinks 2
• Sugar alcohols (sorbitol, mannitol) used as sweeteners 3
• Added fructose or fructans in flavorings 2
• The liquid form allows rapid delivery of these fermentable carbohydrates, explaining why liquids trigger symptoms more than solids 1

Recommended Diagnostic Approach

Start with a 2-week dietary restriction trial—this is the simplest and most economically sound diagnostic approach 1, 2:

1. Eliminate high-FODMAP foods for 2 weeks 2:

   • Sugar-sweetened beverages with high-fructose corn syrup 2
   • Foods with added fructose as sweeteners 2
   • Foods containing fructans 2
   • Sugar alcohols (check ingredient labels for sorbitol, mannitol, xylitol) 3

2. If symptoms resolve, this confirms FODMAP intolerance; if symptoms persist, consider hydrogen breath testing measuring hydrogen, methane, and CO₂ to diagnose specific carbohydrate intolerances or small intestinal bacterial overgrowth (SIBO) 3, 2

3. Rule out secondary causes before accepting a primary diagnosis 1:

   • Your history of ulcer disease and current PPI use raises the possibility of SIBO, as decreased gastric acid secretion is a risk factor for SIBO 3
   • SIBO can cause fermentation of any carbohydrate or protein substrate, producing gas, bloating, and watery diarrhea 3
   • Consider testing for Helicobacter pylori if not previously done, as this infection can alter gastric function 3

Management Strategy

Implement a low-FODMAP diet with guidance from a trained gastroenterology dietitian 2:

• Avoid sugar-sweetened beverages entirely 2
• Switch to black coffee or coffee with small amounts of lactose-free milk if needed 1
• Ensure the diet remains nutritionally balanced despite restrictions 2
• Monitor for development of restrictive eating patterns 2

If dietary management alone is unsuccessful after 2 weeks, evaluate for other gastrointestinal disorders 2:

• Consider breath testing for SIBO given your PPI use 3
• If SIBO is confirmed, antibiotic therapy with rifaximin or metronidazole may be considered, though these are not FDA-approved for this specific indication 3

Important Considerations About Your PPI Use

Your proton pump inhibitor (PPI) for acid reflux may be contributing to your symptoms 3, 4:

• PPIs cause profound hypoacidity and hypergastrinemia 4
• Gastric hypoacidity increases gut bacterial infections and can predispose to SIBO, which would explain fermentation-related symptoms 4, 3
• The change in coffee taste you noted since starting the PPI may reflect altered gastric pH affecting taste perception 5
• Continue your PPI as prescribed for reflux control, but discuss with your physician whether SIBO evaluation is warranted 3

What to Avoid

• Do not eliminate all dairy products without professional nutritional counseling, as this significantly increases the risk of calcium and vitamin D deficiency 1
• Do not rely on symptom reports alone—objective testing or systematic dietary elimination is essential 1
• Do not ignore the possibility of IBS—visceral hypersensitivity can cause symptoms independent of any specific malabsorption 1

When to Seek Further Evaluation

Consider additional medical evaluation if 3:

• Symptoms persist more than 3 days per week and disrupt usual activities 3
• You experience weight loss (particularly concerning given your age and ulcer history) 3
• Chronic diarrhea or constipation develops 3
• Severe abdominal pain or bloating worsens 3
• Nausea and vomiting occur, suggesting possible gastroparesis 3