L.G.
Dear M.
When my aunt was losing her hair from stress and an illness I spoke with a Roma woman about it. She told me to make a thick paste of organically grown tobacco and cover her head with it once a week. Put a kerchief over it and let it sit as long as it is wet. It did work. I hope the tobacco does dye you hair. We used oil to keep it from her hair but some did dye it.
Other than that it's Vitamin A and E taken internally. That I know about.
On the medical side you could use Rogaine.