The straight stuff or the timed-release?
Last time I bought niacin I had to go to THREE different drug stores before I found the real nicotinic acid, plain vanilla flush-yur-brains out niacin.
All the other stuff was either the niacinamide no-flush or the timed-release type.
I take about 500 mg a day just to warm me up a bit.
Straight stuff, 2 grams a day.
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You get a bigger flush if you take it every other day