I'd talk to a pharmacist.

I'm using rhinocort, a nasal spray antihistamine, for hayfever. It's a class A drug when used as a spray because apparently not much of it gets absorbed into your bloodstream from your sinuses. Certainly it turned spring hayfever from unbearable into OK for me. My ob and a pharmacist agreed it would be OK for me to use.

So I gather that maybe it depends on the drug, but certainly some nasal sprays are relatively safe. Probably rhinocort doesn't help much with a cold, it's more for hayfever, but maybe there is something else that would help with a cold.

(Yay for class A drugs - not perfect, but not a big risk either - just like crossing the road!)