I bought a Now Foods 500µg jar as I saw a thread where niacin was discussed to help with certain symtoms, but now I have forgotten which

Anyways, I read that this is a far to big dose to start with, and one can have bad reactions to it. So I opened the capsule and took about 1/10, which should be about 50µg.
15 minutes later I had more or less forgotten about it, but then my face became weird deluxe. Then I remembered somehting about flushing and red skin, and I though could this be it. I searched for flushing, and saw that it was normally in the face region. I relaxed my shoulders 50 cm as I was getting a bit scared that I was getting some sort of allergic reaction.
I also read somewhere that the flushing should mean we have enough of it... if it dillates the blood vessels, it must be very good for headaches?! No?