There are so many allergens in the barley which could harm the health. The wheat and barley can be co-relate with each other so if you have allergy with barley then test for both wheat and barley. You generally consume barley in the form of various dishes. But the excess level of barley in the body of human can harm the health. There are so many allergen include in the barley which is harmful for the stomach. Barley is the fourth most important grain in the whole world after wheat, maize and rice.