The inflammation and swelling of the membranes lining the sinus cavities is responsible for sinus congestion. The membranes begin to produce excess mucus in order to flush out the cause of the irritation, whether it is viral, bacterial or allergen. It is important to keep the membranes moist when congestion begins. If the membranes become dry the irritation will increase and the congestion will get worse. Keeping Sinus Membranes Moist There are several solutions to the dryness of sinus membranes.