University of Virginia researchers gave 47 cold sufferers a spray containing this ingredient (in Dristan and other brands) for five days and compared those people with 47 other snifflers, who used a saline spray. The preliminary data suggests that oxymetazoline has a potential antiviral effect: Cold virus levels in those exposed to the ingredient started to drop by day two, while the virus count peaked in the others two to three days after infection—a difference that may help stop the problem from spreading to your sinuses.