I used black seed oil aka black cumin oil or nigella seed oil. I actually didn't start taking the oil with the intent of curing white tongue. I had been trying to treat white tongue for the past few weeks with oregano oil, sea salt, coconut oil pulling and ACV. none of them seemed to work, except for oregano oil, but that was temporary (literally would only last for minutes after putting it directly on my tongue).
I drank ~10ml of black seed oil yesterday by the suggestion of my friend, just for general health purposes, not to target anything. today I saw DRAMATIC improvements in my tongue!!! Almost totally normal! Incredible... I drank another 10 ml today. funny enough, I've been waiting for an online order of pao d'arco tea to come in. I was hoping that would help, but I guess I already found my cure. I'm going to keep taking this stuff and rubbing it everywhere else to see what other magic it can work. just look up the case study of the man who was cured of HIV by taking black seed oil with honey and you too may be inspired by the possibilities of black seed oil.