If your underwear is up around your sinuses, you’re wearing it too high and the pain is from buying too small a size.
I, too, read it as sinus pain underwear - idiot, uhhhh, me 
How long are dives? I’ve never seen Sudafed in a dose less than 12 hours.
Now, I realize that in reality it may have optimum performance for only 7-8 hours or so.
I am not trying to argue with the experts, I just can’t think of a biological way a 12 hour dose can go into your system, work for 1 hour, and then suddenly stop working 30 minutes later.
That’s not really what the experts are worried about. The problem is that pseudoephedrine may increase susceptibility to oxygen toxicity. While an antihistamine, pseudoephedrine is also a type of drug called a sympathomimetic (i.e. it mimics the action of substances produced by your sympathetic nervous system), and research has shown that sympathomimetics increase oxygen toxicity and oxygen convulsions in rats. No human studies have been done, but taking something that might increase your susceptibility to oxygen toxicity and then diving on increased oxygen mixtures is a bad idea. Whether it’s bad or not when diving on standard air is uncertain.
Cite: http://www.diversalertnetwork.org/medical/articles/article.asp?articleid=51
I read it as “Sarah Palin Underwater”. Possibly because it’s such an appealing idea, for a given depth of water. After all, it worked for nuclear waste.
I’m going to call her “Sinus Pain” from now on.
Holy shit! Me too, that’s what I came here to post. Too fuckin’ funny.
Count me in, it just happened to me as well. If you glance at it quickly it does look like that!