I have tried the the "no poo" thing. It totally didn't work for me. When I'm home I avoid washing my hair as long as possible. I just bought some argan oil shampoo with no sulfites, cruelly free, vegan... Not for dandruff though. I have to wonder if dandruff isn't an allergic reaction to something... ?
40 years ago (as a teen) I saw a dermatologist because of my dandruff. He was almost a "family doctor". He also treated my brother and father. and he prescribed the same extra strength shampoos and a cortisone solution that you put directly on the scalp.
Later on, when I was on my own I couldn't afford the special stuff. But it was basically the same things and in H&S blue and H&S white. just twice as much active ingredients. It never eliminated dandruff but it reduced it to un-embarrassing levels.
Then as I became more concerned with animal cruelty I tried to get off the H&S. Did a bunch of little home experiments and for the last several years I have been alternating between H&S white and Jason's, with reasonable results.
I'm glad we are discussing this. I feel like I have become complacent in this area. And bought my first alternate cruelty-free shampoo in years last week at Trader Joes. Tried the ACV rinse. And ordered another shampoo from Amazon to experiment with. May even go back to Trader Joes and buy their conditioner.
Right now I'm pretty good except for my chin. ( I have a beard). And my chin has always been a problem area. But this hasn't even been a week in the testing. Also, I probably didn't use the ACV rinse on my beard.
Anyway, I don't think dandruff is an allergic reaction. My doctor told me it was a fungus, 40 years ago and that seems to be the medical consensus. Being that my brother and father had it I thought maybe I "caught" it from them. But my mom and sisters are dandruff free. So it is probably something hereditary. Maybe our immune system can't fight off the fungus as well. I also have toenail fungus - which I think I did "catch". but I think that maybe lends some credibility to the immune system theory. My dad had toenail fungus, too.
I found this article just now and it seems to have some really good ideas, too.
https://www.medicalnewstoday.com/articles/152844.php