Hello, registered an account to provide my experience regarding long term cetirizine, niacin flush and aspirin. This may confirm / disconfirm the theory of this thread.
due to histamine intolerance, i took oral cetirizine everyday for over 14 years. 14 years ago i was NW1, now i am NW5. As you can see, it did nothing for my hair loss.
3 years ago i found out about niacin flush. Taking it every 2-3 days i was able to stop cetirizine altogether, something i couldnt miss a single dose before.
In terms of scalp itch, cetirizine did nothing. Niacin flush alleviated it by a good 70%. Stopped using the latter in early 2019, because i completely forgot it existed. (im forgetful)
Fast forward to 2019 July, i started taking 3x baby aspirin everyday and still do today. it was able to completely halt any scalp itch. The itch that accompanied with my hair loss for the last 14 years. It was amazing. I did not lose any more hair during this time. BUT never experienced any regrowth either.
During this time i could eat scalp-itch-inducing junk food like chocolate and pizza.
In regards to dandruff, i used to think it causes scalp itch and has a hand in hair loss, but aspirin never took the dandruff away, and i did not lose any more hair with them.
Lastly, theres as much scalp sebum 12 hours after shower as before. But again I did not lose any more hair because of it.
Wish I knew about aspirin 14 years ago.