Food Intolerance: What It Is, How It Differs from Allergies, and What to Do

When your stomach feels bloated after dairy, or you get a headache after eating wheat, it’s not always an allergy—it could be food intolerance, a digestive system reaction to certain foods that doesn’t involve the immune system. Also known as non-allergic food hypersensitivity, it’s far more common than true food allergies, yet often misunderstood. Unlike allergies, which can trigger life-threatening reactions like swelling or anaphylaxis, food intolerance usually causes discomfort—bloating, gas, diarrhea, nausea, or headaches—that shows up hours after eating. It’s not dangerous in the short term, but it can make daily life miserable if you don’t know what’s causing it.

Two of the most common types are lactose intolerance, the inability to digest the sugar in milk due to low levels of the enzyme lactase, and gluten sensitivity, a reaction to gluten that isn’t celiac disease but still causes gut distress and fatigue. Many people think they’re allergic to gluten, but unless they have celiac (an autoimmune disorder), it’s likely intolerance. Other triggers include histamine-rich foods like aged cheese or fermented products, sulfites in wine, and artificial sweeteners like sorbitol. These don’t show up on allergy tests, so people often go years without answers.

What makes food intolerance tricky is that symptoms are delayed and vary by person. One person might feel fine after eating eggs, while another gets migraines. There’s no single test for most types—doctors usually recommend elimination diets, where you remove suspect foods for weeks and slowly add them back to see what triggers symptoms. It’s not glamorous, but it works. And while medications won’t fix the root issue, some supplements like lactase pills or digestive enzymes can help manage symptoms when you can’t avoid the trigger.

You’ll find real-life advice in the posts below—from how to read labels to avoid hidden triggers, to what to do when you’re unsure if it’s your gut or your meds causing the problem. We cover practical steps, common mistakes people make when self-diagnosing, and how to tell the difference between a reaction to food and a side effect of a prescription. Whether you’re dealing with bloating after every meal or just trying to figure out why you feel off after eating out, these guides give you the tools to take control—without guessing.