Gluten “Allergy” Gluten is a protein found in grains, such as wheat, barley and rye. Symptoms of celiac disease include severe diarrhea after eating gluten-containing products, a rash, severe weight loss or failure to properly gain weight, and abdominal pain.Click to see full answer. Then, how do you know if you are allergic to gluten? Here are the 14 main signs and symptoms of gluten intolerance. Bloating. Bloating is when you feel as if your belly is swollen or full of gas after you’ve eaten. Diarrhea, Constipation and Smelly Feces. Abdominal Pain. Headaches. Feeling Tired. Skin Problems. Depression. Unexplained Weight Loss. Beside above, how long after eating gluten do symptoms start? For most people, the symptoms persist for two to three days before finally clearing up: A hefty price to pay for consuming a minuscule bit of gluten. As a person suffering from celiac disease, you probably are familiar with your own set of symptoms. Keeping this in view, can you suddenly become gluten intolerant? “If somebody tested negative for celiac disease at age 50, and then develops symptoms at age 65, test them again because you can develop gluten intolerance at any age.” Blood tests that look for the presence of certain antibodies are usually the first step in making a celiac disease diagnosis.How does gluten affect the body?Gluten is a protein found in many grains, including wheat, barley and rye. People with celiac disease have an immune reaction that is triggered by eating gluten. They develop inflammation and damage in their intestinal tracts and other parts of the body when they eat foods containing gluten.