Hi Cami,
I've used Niacin since Nov 2002, 500 mg Sundown brand, and I get the flush almost every time. With me, the flush lasts for about 10 minutes, starting with my ears, all over my scalp, then to the rest of my body. I take it when I take all my other supplements, and I've noticed that my skin is buttery smooth and my face is really radiant (glows).
I have what's called 'thin blood' b/c my hands and feet are always cold, so Niacin ensures that I have adequate circulation at least once per day.
As for hair growth, I haven't noticed extraordinary results. My growth rate hasn't sped up or slowed down. For me, it's just piece of mind - I know my scalp is getting the blood flow it needs b/c I get that warm tingling feeling
. Also, since I take it with my other vits, it moves the nutrients to my blood cells along with it. For example, when I take biotin, multi-vit, vit e, etc with Niacin, all of those travel through my system at a fast pace along with the Niacin, feeding my hair follicles, skin cells, etc.
IMO, Niacin works great. I wouldn't recommend it to anyone else b/c if it backfires on them, I'll be the one to blame. So...If you are not experiencing ill effects, the choice is yours. Keep in mind that it is a B vitamin, so it's water soluble (you can't overdose - whatever's left over will be excreted) BUT as my label states: "Diabetics should consult a physician prior to taking large does of Niacin."