I'm curious about the effects of hair tonic.

There are many types of hair tonics on the market, and I'm not really debating which one to buy, but I am curious about their effectiveness. I've heard that yeast is good for alleviating hair loss, but is it actually effective?

Also, I used tonic frequently last summer, but my hair started getting greasy over time. I tried to detangle it with my hands, but it just made it stickier and collected a lot of dust, so I stopped. I would appreciate it if you could let me know of any products that feel refreshing when sprayed, absorb quickly, and have been effective.