regarding your edit there, I guess most people stopped reading at 'essential oils' without knowing where this was going.

this is one (the only?) actual medical use for these things - their main thing is that they smell in a certain way that is consistent, so you use them to retrain your sense of smell. that's it. no taking internally or applying to skin or whatever. just take the stopper off the wee bottle, sniff and repeat for as many bottles as you can be arsed.

when I had covid-19, I didn't have so well defined scents on hand, but I did have several colognes I could sniff, and I knew fairly well how they were supposed to smell and could use those to gauge my senses. fun times, they were...