Other people experience an allergic reaction to house dust, dust mites , animal dander or mold spores. When a person with allergies inhales an allergen, the body's immune system reacts abnormally to the allergen. The allergen, such as pollen, triggers the nasal membranes to release histamine and other chemicals. Histamine dilates the small blood vessels of the nose and fluids leak out into the surrounding tissues, causing runny noses, watery eyes, itching, swelling and other allergy symptoms. The nose normally produces mucus, which traps substances like dust, pollen, pollution, and germs such as bacteria and viruses.
Mucus flows from the front of the nose and drains down the back of the throat.
When allergies attack, mucus production becomes excessive, causing a runny nose. Itching and sneezing are your immune system's natural response to rid your body of its enemies, including allergens. There is no specific cure available, but there are several options for treatment. Other treatment options include avoidance of allergens, medication and immunotherapy, also known as allergy shots. When dusting, make sure to use a damp cloth.