I have worked my way up to three drops at a time and that took awhile! I admit I burned my mouth once but I knew it was my fault because I was not careful.There is a warning label in red for a reason. It will heal up like any mild burn. In the future I would only do 1 drop in a whole filled up bath. I have done that with no problems but I have been using Oregano for several years. Don't let the burns scare you away from using it, its the best herb known to man(in my opinion)