@gallahad & @bronchiectasaurus Yes, conditionally. I use nasal lavage (VERY gently) whenever I have an upper respiratory infection - learned long ago that is the only way to prevent a sinus infection for me. Also, occasionally if I have been overexposed to pollen or dust. Then I usually rely on a bottled sterile nasal saline solution.

Two things my ENT's have taught me over the years - gently with no pressure behind the water and absolute cleanliness to avoid introducing new germs and to avoid forcing water into the sinuses.