Tolerance & dependence

 

Tolerance

Tolerance for methamphetamine occurs within minutes, meaning that the intensely pleasurable effects disappear even before the concentration in the blood falls significantly. This lures users into trying to maintain the high by bingeing on the drug repeatedly.

Dependence

The other significant health consequence for users of methamphetamine is a strong dependence on the drug. With repeated use the dopamine receptors in the brain are damaged, meaning that the brain is unable to register the same levels of pleasure and satisfaction of any life experience (not just the effects of drugs) as it did before using methamphetamine. This sets up the cycle of dependence, where users "need" the drug in order to feel pleasure, or simply to overcome the feelings of withdrawal.