My onset of tinnitus coincided with my use of Rogaine. BUT! It may, it probably is unrelated. Hearing loss is the primary cause of tinnitus and hearing loss occurs w/age ... so does hair loss. Correlation is not always causation. I stopped using Rogaine and the tinnitus roared!
My approach to tinnitus however has been effective: DO NOTHING ABOUT IT. No therapy, no worry, no cover sounds, no diet, no drugs, no hope, no fear, no thought. Profound NOTHING. Two things occurred in the years since. One, my tinnitus frequently goes away for an hour, a week, a day, 3 days. No pattern. However, I am not aware of when it comes and goes because (see my do nothing strategy), my brain over the first 18 months just got bored with it. I am unaware whether it is on or off because my attention has gone off of it. Because I'm writing this, I am just now aware of a low level today, I will forget whether it's on or off a few minutes from posting this. I recommend the absolute nothing strategy. (and probably, Rogaine has nothing to do with tinnitus, I just got sick of applying it)