Genes and chemical makeup
while I avoids drug tolerance by rotating what I use every time I get high and change the class of drug I use every time I get high for people who use one drug and never switch they have to get crafty on how they keep tolerance down while being as frequent as possible or have to have good genes
its not always a good thing though depending on what it is
sometimes its the immune system:
and its just really weak at destroying unknown chemicals in the blood stream (bad thing Iv actually done a treatment where I inject snake venom weekly into myself to stimulate my immune system making my body impenetrable of course it mean's sometimes drugs get destroyed without warning
sucks but its worth it since I haven't had a cold in years)
sometimes its purely the brain :
tolerance builds up when the brain gets used to a certain chemical the brain is so crafty it even associates this with location (its why some heroin users od when they shoot in a new place and different setting they are used to) Which also means that the brain in question if it does not easily build tolerance its not very good at adaptability (also a bad thing)
sometimes it is the chemicals in associated with the way you are taking the drug:
sometimes people have more of a chemical in say the stomach that makes breaking down a certain chemical easier and therefore the user getting less effect and with more use overtime the body adjusts to this chemical producing more of that same chemical to help break it down even easier so if the stomach in question is not doing this again red flags
I would recommend rotating drugs like I do and stimulating the immune system to keep getting while at the same time staying healthy (not saying to inject snake venom but try take supplements that help with stimulating the immune system this would be especially a problem say if you were sharing needles with a weak immune system in this hypothetical world chances of HIV would skyrocket)
-Streetcow