A few years ago I got a reverse block . Caused a nose bleed and headache, luckily it resolved during a long stop but back on the boat I looked like I'd got in the ring with Mike Tyson, bruised above and below the eyes. I did'nt have a cold or even know I was bunged up. Now if I think there's a chance of blocked sinus's I take Sudafed each morning a few days before the dive but not on the day of the dive, it keeps me cleaned out just in case, but won't have any chance of wearing off while I'm down.
