Niacin (B3) Health Benefits

Pellagra:

I am confused between niacin and niacinamide. Many posts here are saying that niacin is the only form that will not damage the liver, but Ted's post below says the opposite:

https://ted.earthclinic.com/supplements/niacin.html

Please advise what to do as I need to use it for my 18 years old finger skin inflammation.