Hello, my name is Jack. Male age 21. A strange yellow/white substance has been growing on my armpit hair. Not all hair is affected for some reason but it has been consistently troubling me. I believe it to be some sort of fungus that feeds on the sweat of my under-arm ( may also cause excess sweating? ) I ve done a bit of research but found little that solidly matches this. I ve tried shaving, which helps temporarily but generally within a couple of weeks it begins to appear again. i ve tried shampooing in case it was a build up of dead skin cells which only mildly improved the situation. One of the popular answers is a reaction that happens when my sweat mixes with deodorant but I rarely use deodorant so i highly doubt that is the cause. There is no itching or irritation of the affected area, the only effect would appear to be excess sweating in situations one wouldn t ordinarily sweat. also the aforementioned yellowy white-ish substance similar to dead skin cells ( or perhaps what you d find in a blackhead? ) please share your thaughts.