I take 500 mg of full flush Niacin, at least once a day, sometimes twice, and have been for a couple of years. I only get a small flush but feel fantastic afterwards. My cholesterol has normalized, blood pressure is much lower, and I am far healthier for it.
The best way to ease that histamine burning is to take an aspirin about 20 to 30 minutes before. Bromelain works but possibly not quite as good. Quercetin also helps reduce the histamine reaction.
I actually do NOT recommend taking the Full flush Niacin and nicotinamide at the same time. There is not a lot of difference between the histamine reaction for 100 mg and 500 mg.
In the best study ever, 3000 mg a day reduced mortality from ALL causes by 90 percent, but always be under the observation of a knowledgeable medical professional if you do this.