. And the fact it re-grows hair was discovered quite by accident. You may as well ask "How did the universe begin?"
Originally intended as a drug to lower blood pressure by dilating the blood vessels. Minoxidil had an interesting side effect -- it worked on the structure of hair follicles -- causing hair to begin to re-grow.
The effect was profound enough that minoxidil was approved by the FDA (Food and Drug Administration) and recommended by AAD (American Academy of Dermatology) to be sold as a hair re-growth product that works!
So how does minoxidil work? The 3 reasons it is believed it works are; it:
opens up the hair follicles -- stimulates cellular activity around the hair follicle -- either causes or allows the re-growth of hair
It works for both men and women. Some folks see spectacular results while others may experience disappointment. The main reason for that is the although minoxidil is proven to re-grow hair -- by its self it cannot stop continued hair loss! You need to add one more step.
You need a two pronged attack -- minoxidil applied as a topical solution directly to the thinning area (if you are completely bald -- it will not work) and at the same time you take a specific oral supplement, designed to stop hair loss. You create a very effective one two punch.
Why a two tier method is needed?
Minoxidil will re-grow hair, but if you have not taken steps to reduce or eliminate the cause of the actual hair loss. The newly re-grown hair will simply fall out again. The oral supplement is the part that stops the hair loss. Using just minoxidil or the oral supplement -- instead of both together will produce major disappointment in the results and disillusionment with the products purchased.
You have to give it time. Results will only become apparent after a number of months. When you do see results if you stop the regime normal hair loss will return and hair hair will become thin again. (The same as stopping you blood pressure lowering medication will result in your blood pressure going back up).
The people that experience the best results -- both men and women -- are the ones that begin using the anti hair loss therapy at the first sign of hair thinning. The longer you wait the more difficult to recover the hair you want.
In conclusion answering the question -- how does minoxidil work -- is impossible -- no one knows. What we do know is that it works best for restoring hair when used in a combination therapy.