It is not necessarily mold or toxins that increase your flush. The skin has mast cells that produce histamines and prostaglandins which is where much of the itching comes from. I will take an aspirin with my first daily dose of Niacin.
I actually came to love the Niacin flush after a while. Even at times become euphoric. What I found is that a few hours after after the first flush from taking 500 mg, I would take another 500 mg. That way, the histamines and prostaglandins do not have time to build back up. My arteries became more relaxed and blood pressure lower.
As a warning, not everyone can take it. The liver has to metabolize the niacin as well as the histamines and prostaglandins so that it can become overloaded. keep an eye on your liver enzymes.
Taking Full flush niacin 3 times a day can result in a 90 percent reduction in mortality, provided that there are not any liver issues.