Have had allergic rhinitis for a month. It's like a permanent cold. You can't sleep, you can't breathe properly.
Here's my advice if you get it (or hay fever).
I tried a medium-strength steroid spray. Useless. I took a course of steroid pills. Useless. I tried a full-strength steroid spray. Useless.
A little bit of research on Google led me to the sneezer beam. This is a battery-operated device. A probe goes up each nostril. You switch it on for 3 minutes twice a day. The idea is that there are two different frequencies of light that specifically counteract the histamine build-up, or something. Your nose glows red.
Anyway, it works. After a week, I'm 90% better and can sleep again and breathe reasonably clearly. Absurd.
My wife has used one of these for ages. No idea how it works, makes her look weird in the dark, but it's certainly effective.