It's sold as an anti allergic nasal spray (it definitely helps with my light dust allergy at night) but it also works very well when suffering from Rhinitis.
Also doesn't build dependence, which is a big plus.
I have a few times taken opioids for weeks on end because I had very invasive surgery with quite extraordinary amounts of pain during recovery, and have never felt the desire to take more after the pain stopped being above a very high threshold.
I've known others who have taken opioids for a couple days for something that healed much more rapidly, being very afraid to take them, and had to be sure they disposed of any left because they definitely felt the urge to take more beyond relieving immediate pain.
That sounds like "famous last words". The fact that they don't know of the effects is probably because they carefully avoided looking for them.
I've tried cocaine; didn't like it. I use OTC codeine/paracetamol for pain; I don't need the paracetamol, but you can't buy straight codeine OTC in the UK, so I'm forced to buy a proprietary compound. I'm never tempted to take it if I don't need it.
So it probably sounds as if I'm the type who doesn't fall to addictions; but in fact I've been addicted to alcohol and nicotine for 40 years. I've tried repeatedly to quit both, and failed.
There's just one psychoactive drug I've used that is definitely not addictive: LSD. If you can bear to continue tripping for more than about 3 days, it stops working, no matter how high the dose, and you won't get re-sensitized until several weeks of abstinence.
On the other hand, I tried _one_ cigarette at university, and spend the next day or so with a near constant thought in the back of my head - "I should get some more cigarettes".
Your doctor is right, corticosteroid nasal sprays need to be taken before the onset of symptoms to be most effective. They basally dampen the allergic response and if you already have a bunch of immune signaling molecules bouncing around its too late.