I have used Niacinamide (or Niacin) effectively for arthritis pain. When doing so, I usually take 1500mg either 1x or 2x per day for about a week. Then I cut back.
I doubt the 35mg Grace1 mentioned in her 2017 post (posted below) does anything at all. That is far too little. In order for a vitamin (niacin is vitamin b3) to act as a drug, the dosage has to be far greater than what we normally take. I highly recommend all forms of niacin, especially niacinamide, since that does not cause a flush.
Grace1 (Pdx) on 05/05/2017:
"Some doctors in Montreal found Niacinamide to be a potent fungal and aspergilla's killer. It basically kills Candida infections/pathogenic fungi. This of course is something genuis Ted already knew. Niacinamide is especially effective against candida. The human equivalent dose was 35 mg and it was only administered only once. A second dose of Niacinamide was given 8 hours later. However, even a single dose was effective. While this dose is on the high end for niacinamide, for most people it would still fall under 3g, which is what mainstream medicine officially considers the upper safety limit for niacinamide. Niacinamide can cure Candida infection with a single dose. I think taking caprylic acid a before to first dissolve biofilm and then take Niacinamide and I also took two a dissolved aspirin in a glass of water and took it with the niacinamide this was a strongly effective way to go after it. Of course the obvious stuff which is be on the anti-fungal diet, helps and expect a die off so do gentle detoxification to assist the body in the process of clearing and healing." https://www.earthclinic.com/cures/candida13.html#niacinamide_185779