Using oils and essential oils, you can make most any type of salve you can want for external use on the skin.....basically what ever you believe about a certain essential oil or oil can be added.
For the fun of it I took a base formula and added allot, to make a SORE THROAT Salves and then to that Salve, I added allot, to make a THYROID SALVE and to that, I added "more", including charcoal to make a "cleansing" Thyroid Salve. NOW I knew NO ONE would like charcoal in their salves....that is like taking a paint brush and dipping it in black paint and coating your skin. Would be a "safe" military style 'black-out" of those snipers hiding in the dark..... MY self-experiment is to just see if the skin will absorb charcoal through the skin or if it will be left as a black powder to just fall off after it drys up.
THE ISSUSE with essential oils is making sure they are true steam distilled from herbs and not synthetics---which basically means something this simple---"IF" you purchase essential oils from a name brand company or anyone selling on amazon or in stores or from essential oils websites----ODDS ARE you can only buy synthetics.
Once past the synthetic "thing" and you have real true steam produced essential oils-----IN THE BEGINNING, most all of them should result in your skin "burning" a little or allot, due to the fact your blood stream reacts to everything that touches the skin and the blood will create an acid that will feel HOT and even burn / blister your skin.
Cayenne Pepper, Oregano and many other essential oils should burn badly at first---taste absolutely extreme HOT-----------------but if you use often over many years of time, you will discover even the hottest cayenne PEPPERS have zero heat.......YES, they will still taste hot, but create ZERO HEAT ON YOUR SKIN.....
The 1 exception is your eyes---keep oils/peppers away from your eyes-----even though some people can apply peppers to their eyes---most will never like that.