The route of administration (ROA) has a lot to do with it. Snorting, smoking or injecting meth gives a stronger high than ingesting meth, with a correspondingly higher risk for addiction. Chasing after the high can lead to compulsive redosing, which can keep the user awake for days at a time, often without eating due to the appetite suppression. Sleep deprivation and lack of nutrition are the causes of most harms meth users experience (Stimulant psychosis seems closely linked to sleep deprivation). Medicinal dosages are also much lower than recreational ones, Desoxyn pills start at 5mg.