It seems to depend on the person. My brother claims the effects last a couple hours for him but I swear it only lasts a few minutes for me. I prefer those triple action cough drops from Halls.
How long does chloraseptic spray last? (sore throat/ spray)
Doesn't last that long for me, never did....but if you have a sore throat the time it does last is nice! You might also try letting ice dissolve in your mouth.