For what it’s worth, I have been making my own mouthwash of peroxide and a bit of peppermint oil and a little bit of oregano oil for years. After I brush my teeth I sprayed this concoction into my mouth as far back as I can and under my tongue. Swish around for as long as I can.
Then I take a Q-tip and put peroxide on it, then run this around the inside of my nostrils.
I’ve also been making my own tonic water from cinchona bark, Take zinc vitamin C, quercetin, etc.
Same here except I slow and gently swab as far as comfortable into the sinuses. The same distance as the Corona test swabs without the burning pain. Applied immediately after start of nasal congestion it causes sneezes clearing the mucous and immediately providing normal nasal breathing. Instant relief that can be maintained by four applications daily. Usually after two days it's all cleared up.
I do follow with peroxide rinse/gargle and then cheap 100 proof vodka gargle/rinse. YMMV...but haven't had a bad cold, flu, or bronchial infection in more than a decade. Not prescribed by my docs but was told if it worked for me to keep it up.