Only if you over-use it.
"Normal saline spray" kicks azz on post nasal drip, which unchecked usually turns into a cold or sore throat. I've nipped many a cold onset with this cheap but highly effective product.
The salt kills pathogens by pulling the water out of their structure.
This is the only way to get the salt to the infected area, gargling is ineffective except for the back of the mouth and epiglottis.
My post denotes verbiage from the manufacturer with “ “.
Agree that normal saline, 0.9% NaCl is isotonic and should not dry tissues is used in moderation.
When trying to thwart a cold/sore throat, I like to gargle with a supersaturated NaCl solution. I do not normally use nasal spray/saline or a netti pot. I’m a little skeered about amoeba.