to be effective, how long do you have to leave spironolactone/minoxidil..
- Thread starter The Fluke
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The general rule-of-thumb is that you should wait about 4 hours before shampooing to get reasonably close to the maximum benefit from topical minoxidil, based on measurements of systemic absorption of the drug (frankly, I sometimes wonder just how precisely that's correlated with actually getting minoxidil into the hair follicle itself, but that's an issue for another post! 
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However, that same systemic absorption also occurs more rapidly at the very beginning, and then slows way down after a period of time. A study from several years ago found that with 2% topical minoxidil, about HALF of the amount that was going to be absorbed eventually was already absorbed after only 1 hour! However, my guess is that the standard 5% Rogaine formula will be absorbed a little more slowly than that, and spread-out over a greater period of time.
Bryan
).However, that same systemic absorption also occurs more rapidly at the very beginning, and then slows way down after a period of time. A study from several years ago found that with 2% topical minoxidil, about HALF of the amount that was going to be absorbed eventually was already absorbed after only 1 hour! However, my guess is that the standard 5% Rogaine formula will be absorbed a little more slowly than that, and spread-out over a greater period of time.
Bryan