Otrivin v Nasonex

 I went to the chemist to buy Otrivin and the chemist said I should not use it for more than 3 days because it suppresses the immune system and when i stop using it, my symptoms will come back and possibly worse than before.  She suggested Nasonex.  

Otrivin $12 
Nasonex $20

I had a feeling of being upsold.

This link
https://www.webmd.com/drugs/2/drug-6953-9214/otrivin-nasal/decongestant-spray-nasal/details
Does in fact say
"This medication provides only temporary relief. Do not use more often, use more sprays, or use longer than directed because doing so may increase the risk of side effects. Also, do not use this medication for more than 3 days or it may cause a condition called rebound congestion. Symptoms of rebound congestion include long-term redness and swelling inside the nose and increased runny nose. If this occurs, stop using this medication and consult your doctor or pharmacist."

Otrivin is Xyloetazoline hydrochloride 1mg/ml
Nasonex is mometasone furoate 50mcg/sray

So we assume they are different.

But still the question is HOW does it work and does it suppress the immune symptom and WHY do we get the "Rebound Congestion"?

https://www.medbroadcast.com/drug/getdrug/otrivin

Says "It works by narrowing the blood vessels in the lining of the nose. This helps to clear the symptoms of congestion" 

https://en.wikipedia.org/wiki/Xylometazoline

"Extended usage of xylometazoline can result in decreased effectiveness or a buildup of tolerance against the drug.^[8] The number of receptors decreases, and when the administration of the drug is ceased, chronic congestion can occur; this is called rhinitis medicamentosa, commonly referred to as rebound congestion."

OK So now how about Nasonex

 https://www.rxwiki.com/nasonex

 Nasonex belongs to a group of drugs called corticosteroids, more commonly known as steroids. It works by affecting the immune system to decrease inflammation of the nasal passages.

The medication comes in a nasal spray. The nasal spray is used once or twice daily.

Common side effects include headaches, viral infections, sore throat, and nosebleeds.

 SIDE EFFECTS

Otrivin	NasoNex
Xyloetazoline	mometasone furoate
Xyloetazoline	Steroid
Narrows Blood Vessles	Affects Immune System
Buring & Sting Nose Dryness of Nose Headache Sneezing Trouble Sleeping	Nose Bleed Headache Viral Infections Sore Throat
Rebound Congestion

THOUGHTS

So I think the chemist girl got it wrong telling me Otrivin suppresses the immune system when that's what Nasonex does.