Thats why I think people shouldn't stop trying Niacin after first failed attempt. It might perfectly be the case that they've got Niacin of insufficient quality and because of that there is no effect. My opinion is that at least 2 - 3 different Niacin suppliers need to be tested to draw the conclusion that Niacin is inefficient for POIS-er person.
Victor
I've reported that Niacin didn't work for me when I tried it but that I'll be trying again. The fact that the Niacin gave me a strong flush leads me to believe that there isn't a quality issue with the Niacin. Nicotinic acid should be exactly that if that's what it says on the bottle. If there is significant variation in effectiveness between brands perhaps it is more likely due to the other constituents in the tablets (in the case of my tablets the ingredients are: Bulking agents (Dicalcium Phosphate, Microcrystalline cellulose), Niacin (as Nicotinic Acid), Anti-Caking agents (Stearic Acid, Silicon Dioxide, Magnesium Stearate), Sodium Carboxymethylcellulose, Glycerine, Sodium citrate. One could even hypothesise that its another ingredient present in some Niacin tablets but not others that is doing the job though that's not something I believe at the moment.
Of course I'm speculating but my guess would be that if Niacin hasn't worked for someone (as it didn't for me), it could be for many other reasons:
1. The person is already regularly getting enough Niacin from their diet (we have seen one or two cases on the forum (eg. Jivetalk) where Nicotinic Acid taken regularly (eg. daily) has apparently reduced the effects of a dose later taken before orgasm. (Generally I do think my diet is very good).
2. The person might have a slightly different cause for his POIS that results in the same symptoms. If, for sake of argument, the cause were say the lack of a certain hormone, the reason for that might be a deficiency at a different point along the production chain of that hormone compared to other POIS sufferers but the end symptoms might be the same. (I'm not saying POIS is caused by insufficient quantities of a hormone - its just an illustration of how a subtly different cause could give the same symptoms but require a different treatment, eg an enzyme might be lacking instead of a precursor to the hormone).
3. The person might have a different 'version' of POIS altogether with a completely differerent cause. Variations in symptoms between sufferers have been reported since the forum began (eg. some don't have aches and mainly have cognitive symptoms whilst for others aches are a big problem)
4. There might have been something going on in the body of that person on the particular day /at the particular time that the Niacin was taken that means it wasn't effective on that occasion. Perhaps time of day in the context of that person's routine is important for some reason (as reported by Bitu).
As Victor said, it is important to try a promising potential remedy more than once before deciding it doesn't work for you..