When your body comes across your allergy trigger, your immune system identifies it and launches a chain reaction to defend you. It sends a chemical signal to the mast cells in your body to 'release histamines.' When the histamines leave the mast cells, they boost blood flow in the area of your body the allergen affected. This causes inflammation. This attack on foreign bodies causes symptoms like: coughing, a runny or stuffy nose, and itchy, watery eyes. These reactions are the body's way of pushing the allergen out. In cases of our beloved pets, contact irritants such as pollens, new growth grasses as well as bug bites can induce more-than-normal scratching as well as pots on their bodies denoted as 'hot spots' from excessive licking.