What is black drawing salve for skin boils?

I unfortunatly suffer from frequent boils. Usually in armpits, between thighs and now worse in the back of my head. I have used this on and off. First of all its no miracle cure. The way it works it softens the skin on and around the boil. This theoretically causes the blood to flow easier. Causing the pus to be pushed up and hopefully busting the boil. It doesnt always work though. There has been times ive put it on and the next day it burst. Theres been times ive put it on and it did nothing. There's no way i know for sure if would of bust on its on. I suggest hot compress(which may or may not work) followed by the draw out salve. Leave the salve on for about 2 hours after the hot compress. Do this several times a day for 2 days. IF nothing happens I would just leave the boil alone because at this point its not responding to the treatment and you are just irritating it and the skin around it. Helpful tip if you cant find the Draw out salve in the aisle ask the pharmacist they usually have a tube or two in the back. Since this isnt a hot selling item some pharmacies wont dedicate space to it.