The drug has a flat dose response in that even 0.2mg inhibits nearly the same amount of DHT as 1mg and 5mg. See: physics.upenn.edu/facultyinf … index.html
To reduce the amount of the actual drug introduced into your system, to hopefully reduce any potential “withdrawal” or “shock” symptoms to your body vs going cold turkey off say, 5mg.
Professor Sherman Frankel (the link I posted above) asked the same thing. The FDA basically told him to piss off, claiming the 1mg dose was the best for hairloss, contrary to what was shown in their own studies, as he clearly pointed out. So your guess is as good as mine. More details:
propeciahelp.com/forum/viewtopic.php?t=79
Try using the method as outlined in the FAQ at the top of this site (every 2nd day, 3rd day etc)… however if you very concerned then you could probably try tapering off quickly over a few weeks and then just dropping it completely, rather than tapering over months.
It is unknown wether tapering off vs cold turkey will reduce any potential problems, its just a theory, but one which many prescribe to that take other medications (ie SSRIs – they sugest tapering off over months to reduce withdrawal and shock symptoms).
Ultimately it is your decision, though. If you have decided to quit, understandably you dont want to take the drug anymore than you have to. Going cold turkey is always an option.