There is an interesting article in today's New York Times describing an accidental discovery by an Australian MD. He found that Minoxidil (trade name Rogaine) when taken orally at very low dose levels (~0.25 mg) has the effect of restoring lost hair. Minoxidil for topical use in the form of Rogaine and similar products is sold over-the-counter to apply externally to regions of hair loss. It is also used in pill form to control high blood pressure, but in that form it is prescription only and is taken orally in doses of around 10 mg. Dr. Rodney Sinclair, a professor of dermatology at the University of Melbourne in Australia, has found that Minoxidil is much more effective for hair regrowth if taken orally in doses 1/40 the size of the blood-pressure dose.
The problem is that Minoxidil is a cheap drug. Big Pharma is unlikely to set up human hair-regrowth trials to obtain FDA approval for the new application, because the anticipated profits wouldn't support the test costs. So Minoxidil pills may never be sold in the drugstore for hair regrowth.
There is, however, an opportunity for us self-experimenters to try it. I just ordered 60 x 5 mg tablets of Minoxidil from AllDayChemist in India. I plan to grind up a few tablets and dilute them with sucrose to produce some 250 microgram capsule of Minoxidil, then take one of these daily and observe the effects, if any, on my receding hairline. I'll report the result here in a few months.