question: I want to know if I can take Alka-Seltzer plus severe allergy with allegra. I ve already taken the alka seltzer because i was having a stuffy/runny nose with a lot of sneezing and headache. However, the sneezing and itchy throat are really bad from my allergies. I know the alka seltzer has antihistamine in it so I didn t know if taking the allegra on top of it would be too much antihistamine. I also use nasonex nose spray about an hour ago, but it didn t seem to help at all.