I never take Sudafed when I'm diving. It's got known side effects on mood and anxiety. When I've used it in the past it makes me noticeably short-tempered and impatient. I know other divers that have said the same. There's a good chance of me making bad decisions underwater when I feel like that so I'd rather not touch it. I believe there's been some discussion of it potentially lowering the threshold for a CNS tox as well.