How come every time i sneeze now my asthma acts up?

Possible allergies: It is possible that both your sneezing and your asthma are triggered by allergies.

One airway: The same allergens entering your nose also travel down the windpipe to the breathing tubes in your lungs. Those allergens are caught by allergy antibodies (ige) tethered to mast cells. In the nose mast cell activation results in sneezing & congestion. In the airways mast cells trigger smooth muscle spasm (bronchospasm), swelling & mucous discharge narrowing the airways & causing asthma symptoms.