First of all, it's nice to meet you, Dr. Mikki, PharmD. Always glad to know another diving pharmacist!
Mantasscareme, I can't speak definitively, but I have traveled to quite a few places outside the US and have never had trouble with OTC medications. That being said, I always carry unopened packages and usually have the names of any medications, prescription or OTC, written in English and the native language, when I can find them. Again, nasal sprays look much less like drugs of abuse, so they're more likely to get through any customs checkpoints, but in general, I've never had any problems.
(Of course, when you work in the drug industry you never, ever declare that to customs. I usually say that I'm a business consultant. I had a friend say that she worked for the pharmaceutical industry once, and she had to undergo a full search of her person and luggage. Not too much fun. And that was in Canada!)
Safe ascents,
Grier