Both seem to work for hair growth agents.

So... ?? ... could this contradiction be part of the trouble with the missing link to hair growth?

Does using both topically make any sense at all?

I'll assume the constriction concept has to do with cutting off blood supply to follicle and therefore the DHT in the bloodstream ... or does it have to do with blood getting to the follicle just enhancing inflamation?

And does dilation concept merely deal with the nutrients in the blood reaching the follicle?

Is there anything besides caffeine that may constrict vessels and help hair ... provided one believes that's a good thing?

I've said this before but I'll say it again:

I once read somewhere about a bald guy who received a nasty scalp laceration as a result of an automobile accident. The result was a permanent reduction of blood flow to one side of his scalp. Months later his hair was growing back on the side with the reduced blood flow!

In Belgium there are surgeons and hairclinics offering galeatomie and 'onderbinding'(blood breaches above the ears will be burned, so less blood supply to the head will be the consequence) to the treatment as a solution against hairloss. Belgium is not exactly a third world country. They are a country of rules and laws therefore if such a surgery is even permitted there must be some efficacy for the procedure.

Maybe it would help if we think about it like this. Suppose MPB has a purpose. Suppose there is some benefit to being bald. Suppose what is going on with the balding patient is a simple case of "the body knows best". Perhaps it has something to do with sunlight and the skins ability to absorb more of it? I don't know but just assume for a moment that it has some benefit...or at least it had some benefit thousand of years ago when we were hunter gatherers. Then it would stand to reason that slowing blood flow to the scalp would slow the process of what the body is trying to accomplish. Just like when you slow the blood flow to a cut or a sore...it heals slower. It takes the body longer to accomplish what it is trying to do.

I think what threw us down the path of "more blood flow is good" is minoxidil. It is a vasodilator. However there are many other vasodilators that you could rub on your head but they will not regrow hair. Minox does not regrow hair because it increases blood flow. It grows hair inspite of the fact that it increases blood flow. It works by an entirely different mechanism.

To me vasodilation is just another way of saying inflammation. There also seems to be a difference between short term vasodilation and chronic, long term vasodilation. Short term vasodilation is sometimes good because I believe it can often result in a long term decrease in vasodilation and inflammation.

In the skin there are precursors of inflammation known as histamine precursors. If you apply something that "uses up" the supply of these histamine precursors it will take awhile for the body to replace these. During that period you would have a decrease in vasodilation and inflammation.

For example when you apply a topical form of azelaic acid to the scalp most people will get redness, itching, etc. But if you keep applying it day after day this temporary inflammation will gradually become less and less. Why? To me it seems applying the AA regularly uses up the supply of histamine precursors. The question is whether the AA is "using up" the right histamine precursors.