I would recommend using a weather app/service which also monitors the pollen intensity and avoid high intensity days. Im using Breezy Weather from the F-droid app store.
Also nasal spray/eyedrops before or during the ride helps me a lot, just avoid rubbing your eyes with bare hands. I am using a big single-lense cycling glass to protect my eyes, also good against the wind.
I usually avoid taking tablets as they make me feel drowsy (even the non-drowsy ones)