I take 30mg - 60mg of Sudafed about an hour before the first dive of the day. Even if I`m not congested and I dive 3-4 days a week. I still get a sinus squeeze and sneeze up bloodly mucous. Of course I`m only worried if I was in shark infested waters (haha). It can be quite a shock to students, but the I just explain what a sinus squeeze is, and some of the ways to prevent it. However, if I`m diving for fun I don`t seem to get a sinus squeeze. Must be chasing students up and down, and all around...hmmmmm.