Common Causes of Heavy Breathing. There are countless causes of rapid breathing, but some are much more common than others. Take a look at these more prevalent culprits and see if they could be behind your rapid breathing: Allergies: An allergy is when your body gets irritated by a normally benign material. In the case of allergens that can be inhaled such as pet dander, pollen, or dust, the irritation will be focused in the lungs or bronchial tubes. This causes swelling and possibly inflammation that can lead to heavy breathing.