Try maybe bromelain?
http://www.umm.edu/altmed/articles/bromelain-000289.htm
"Although not all experts agree, bromelain supplements may help suppress cough, reduce nasal mucus associated with sinusitis, and relieve the swelling and inflammation caused by hay fever. Bromelain is approved by the German Commission E for the treatment of sinus and nasal swelling following ear, nose, and throat surgery or trauma."