I have always had my doubts but i have seen a couple times on here that niacin sometimes helps with pios, but i also saw that niacin helps flush for a drug test (which after i bout it was found to be a myth) but i got some to take once a day usually at night because i tried to plan it around my "o" to kill two birds with one stone.
And finally my POIS was significantly less dramatic than usual about 75% less still a little chroic body pains( common symptom of mine) but social interacting and my girlfriend enjoyed me much more:)