+1 to what Pam from Idaho said above.
Except I even took an immersion heater (the sort of metal coil you use in a cup of water), via an outlet converter, boiled the tap water, then cooled it, before adding the saline powder packet. (It is excessive but for small nasal sinuses where water is often trapped after rinsing, I don't want to cultivate a new colony of bacteria to cause other complications. Alternatively if boiling the water is just too much trouble, I'd get distilled (not just bottled) water.) I use a neti pot also as a way to rinse out the stuffy junk from secondhand smoke (different topic, let's not discuss).
The neti pot method washes out the allergens (but doesn't stop the body's histamine response), so when you go back outside you might breathe in more airborne pollen if that is what's causing the rhinitis. So...
If you normally use Claritin for antihistamines (I call it by the generic name "loratadine" because the European drugstore had it labelled as such), it was not too expensive there if you are having an emergency (or reaction to something else) and forgot to bring your own from home.
A few other tips:
1. always carry tissue, and multiple packs (also good for toilets frugal with the paper). I like the 4 ply tissue they have for some brands in Europe, if, like me, you blow your nose like an elephant (try not to do this in some cultures). 2. wash your hair before bed. If the pollen was in the air and got in your hair, and then you roll around on your pillow, guess what you just breathed in, and your nighttime sleep quality is going to be? Or wear a nightcap.
p.s. Using a neti pot takes some practice for most.