To know if you are gluten intolerant, you can look for common symptoms such as irregular bowel movements (constipation or diarrhea), fatigue, stomach pain, nausea, bloating, skin reactions like itchy blisters, unintentional weight loss, and pain or numbness in the limbs. These symptoms occur because gluten affects digestion and nutrient absorption improperly in gluten intolerant individuals, causing discomfort and other systemic effects. However, diagnosis should not be based on symptoms alone. To properly confirm gluten intolerance or celiac disease (a severe autoimmune form of gluten intolerance), medical testing by a doctor is necessary. This includes blood tests for specific antibodies like IgE for gluten allergy, IgA anti-tTG for celiac disease, genetic testing, and sometimes an intestinal biopsy. Importantly, you should not start a gluten-free diet before testing since it can affect test accuracy. If non-celiac gluten sensitivity is suspected, it is diagnosed by observing symptoms and ruling out other conditions. If you experience these symptoms and suspect gluten intolerance, consult a healthcare professional for evaluation and appropriate testing rather than self-diagnosing or eliminating gluten prematurely.