if useing pellets maybe the glue and binders are still in the mix when its done to some small extent causein a alergic reaction.. but tren e pure powder isnt made from pellets and it does it as well so idk just a guess also heard its prolatin buildup constricting the lungs.. maybe the chemical makeup of tren itself when mixed with a solvent creates a mixture that is highly iratating to the lungs/body of a human remeber this was made for cattle not us humans it just hash as shit it all kinds of ways maybe thats it..