Why Isn’t Minoxidil an Oral Medication?

Why isn’t minoxidil taken orally? I’ve always been under the impression that drugs taken orally (like Propecia) get to the root of the problem as opposed to ones topically. For instance, if caffeine theoretically helped hair loss, I would think consuming caffeine would work better than putting caffeine on one’s head.

Minoxidil was originally used as an oral anti-hypertensive medication for the treatment of high blood pressure. It was unpredictable in its use so it was abandoned, but people taking it (women) would notice face and body hair appearing from the oral pills. That is why it is not used orally today, as it has a tendency to drop blood pressure. That even occurs when you apply it topically, as some of the medication is absorbed into the body after a skin application.