If you have celiac disease, you need to completely avoid wheat, rye, and barley, along with any food made from or contaminated by these grains. Gluten, the protein found in these grains, triggers an immune response that destroys the absorptive lining of your small intestine. Even small amounts matter. In the U.S., a product can only be labeled “gluten-free” if it contains less than 20 parts per million of gluten, which gives you a sense of how little it takes to cause harm.
The obvious sources are easy to spot: bread, pasta, cereal, baked goods. But gluten hides in dozens of everyday products you might not suspect, from soy sauce to deli meat to flavored whiskey. Here’s what to watch for.
Grains and Grain Products to Avoid
Wheat is the biggest culprit, and it goes by many names. White flour, whole-wheat flour, semolina, couscous, bread crumbs, and most standard pastas are all wheat products. Less obvious wheat relatives include farro, spelt, kamut, durum, and einkorn. All of these contain gluten and are off the table.
Rye and barley are the other two grains to eliminate entirely. Barley is especially tricky because it shows up as malt, malted barley, malt extract, and malt vinegar. You’ll find malt in some breakfast cereals, malted milkshakes, flavored coffees, and certain herbal teas. If an ingredient list says “malt” without specifying the source, assume it comes from barley.
Where Gluten Hides in Processed Foods
Gluten works as a binder and thickener in processed foods, which means it turns up in places that have nothing to do with bread. Processed lunch meats, deli cold cuts, hot dogs, salami, and sausages frequently use fillers that contain gluten to hold ingredients together and create an elastic texture. Imitation seafood (like crab sticks) and many veggie burgers, plant-based sausages, and seitan are common offenders. Seitan is literally made from wheat gluten, so it’s one of the worst choices for anyone with celiac disease.
Additives on ingredient labels can also signal hidden gluten. Watch for hydrolyzed plant protein, hydrolyzed vegetable protein, textured vegetable protein, edible coatings, and modified food starch (unless the label specifies corn or potato). These ingredients may be derived from wheat, and manufacturers aren’t always required to spell out the grain source. When in doubt, check whether the product carries a certified gluten-free label or contact the manufacturer directly.
Sauces, Condiments, and Seasonings
Standard soy sauce is made by fermenting wheat and soybeans together. This is one of the most common hidden gluten sources in everyday cooking. Fermentation does not remove gluten, and the actual gluten content of fermented soy sauce can’t be reliably measured with current testing methods. The FDA has stated that no scientifically valid method exists for precisely quantifying gluten in fermented foods. In the U.S., products containing wheat-based soy sauce cannot legally be labeled gluten-free. Use tamari (check that it’s labeled gluten-free) or coconut aminos as substitutes.
Other sauces and condiments to scrutinize include gravy (often thickened with wheat flour), cream-based soups, many salad dressings, teriyaki sauce, hoisin sauce, and some marinades. Malt vinegar, made from barley, contains gluten, while most other vinegars (white, apple cider, red wine, balsamic) are safe. Spice blends and seasoning packets sometimes contain wheat flour as an anti-caking agent, so read labels carefully.
Beer and Flavored Alcohol
Conventional beer is brewed from barley or wheat and contains gluten. This includes lagers, ales, stouts, and porters. Beer labeled “gluten-removed” is also risky. These products start with gluten-containing grains and are processed to reduce gluten levels, but available testing can’t reliably confirm how much gluten remains. Experts at UChicago Medicine recommend avoiding gluten-removed beer entirely and choosing beer brewed from naturally gluten-free grains like sorghum, rice, or millet instead.
Wine is naturally gluten-free. Most distilled spirits, including vodka, gin, rum, tequila, and most bourbon, are also safe because the distillation process removes gluten proteins. The exception is flavored spirits. Flavoring is added after distillation, which can reintroduce gluten into the final product. Cinnamon-flavored whiskey, for instance, is likely not gluten-free. If you’re considering a flavored liquor, check with the manufacturer before drinking it.
The Question of Oats
Oats don’t naturally contain the same gluten protein found in wheat, rye, and barley, but they do contain a related protein called avenin. For most people with celiac disease, oats are safe. However, research published in the journal Gut found that nearly a third of celiac patients experienced symptoms linked to immune activation after consuming oat protein, with reactions increasing at higher doses. In about 3% of participants, oats triggered a full inflammatory response similar to what wheat causes. Severe reactions like vomiting after eating oats may signal that you’re in this minority and should avoid them.
There’s also the contamination problem. Conventional oats are frequently grown near wheat fields or processed on shared equipment, making cross-contamination common. If you do tolerate oats, look for oats specifically labeled “purity protocol” or “gluten-free.” These come from dedicated farms and facilities that prevent contact with wheat, rye, and barley throughout the entire supply chain.
Cross-Contamination in the Kitchen
Even when you buy the right foods, how you prepare them matters. Research from the Celiac Disease Foundation tested several common kitchen scenarios and found that cooking gluten-free pasta in the same water used for regular pasta caused gluten levels to spike as high as 115 parts per million, nearly six times the safe threshold. Simply rinsing the gluten-free pasta under running tap water afterward dropped levels below 20 ppm, and rinsing the pot with fresh water before reusing it made gluten transfer undetectable.
Other scenarios were less risky than expected. Toasting gluten-free bread in the same toaster as regular bread kept gluten levels under 20 ppm even with visible crumbs present, and using a knife that had cut gluten-containing cupcakes to then cut gluten-free ones also stayed below the threshold in most tests. That said, the simplest and most reliable approach is basic kitchen hygiene: wash pots, pans, and utensils with soap and water before preparing gluten-free food, and have everyone handling food wash their hands first.
Medications and Non-Food Products
Gluten in pills is a common worry, but the actual risk is extremely low. The FDA has found no oral medications currently marketed in the U.S. that intentionally contain wheat gluten or wheat flour. A very small number of drugs use wheat starch as an ingredient, but even in those rare cases, the FDA estimates that a single dose would contribute no more than 0.5 mg of gluten. For context, that’s less than what you’d get from one serving of food labeled gluten-free.
If you want to verify a specific medication, check the inactive ingredients section on the “Drug Facts” label for over-the-counter products, or the “Description” section on prescription labeling. If wheat gluten and wheat flour aren’t listed, the product should not contain enough gluten to cause harm. Lip balms and cosmetics occasionally contain wheat-derived ingredients, but these only pose a risk if they’re ingested, making lipstick and lip products the main ones worth checking.
Why Complete Avoidance Matters
When someone with celiac disease eats gluten, even a small amount, the immune system attacks the lining of the small intestine. Specifically, gluten proteins get modified by an enzyme in the gut wall, making them highly visible to immune cells. Those immune cells launch an inflammatory response that flattens the tiny finger-like projections (villi) responsible for absorbing nutrients. Over time, this destruction leads to malabsorption of vitamins, minerals, and calories, which can cause problems ranging from fatigue and bone loss to anemia and neurological symptoms.
The damage is cumulative and happens whether or not you feel symptoms. Some people with celiac disease have obvious digestive distress after eating gluten, while others feel nothing but are still sustaining intestinal damage. This is why strict, consistent avoidance of all gluten sources, not just the obvious ones, is the only effective treatment.