Since both natural rewards and addictive drugs induce expression of ΔFos B (i.e., they cause the brain to produce more of it), chronic acquisition of these rewards can result in a similar pathological state of addiction.
ΔFos B is the most significant factor involved in both amphetamine addiction and amphetamine-induced sex addictions, which are compulsive sexual behaviors that result from excessive sexual activity and amphetamine use.
Methamphetamine properly refers to a specific chemical, the racemic free base, which is an equal mixture of levomethamphetamine and dextromethamphetamine in their pure amine forms.
Methamphetamine use was found to be related to higher frequencies of unprotected sexual intercourse in both HIV-positive and unknown casual partners, an association more pronounced in HIV-positive participants.
These findings suggest that methamphetamine use and engagement in unprotected anal intercourse are co-occurring risk behaviors, behaviors that potentially heighten the risk of HIV transmission among gay and bisexual men.
As dry mouth is also a common side effect of other stimulants, which are not known to contribute severe tooth decay, many researchers suggest that methamphetamine associated tooth decay is more due to users' other choices.
They suggest the side effect has been exaggerated and stylized to create a stereotype of current users to deter new ones.
Heavy recreational use of methamphetamine may lead to a post-acute-withdrawal syndrome, which can persist for months beyond the typical withdrawal period.
Unlike amphetamine, methamphetamine is neurotoxic to human midbrain dopaminergic neurons.
Internationally, the production, distribution, sale, and possession of methamphetamine is restricted or banned in many countries, due to its placement in schedule II of the United Nations Convention on Psychotropic Substances treaty.
While dextromethamphetamine is a more potent drug, racemic methamphetamine is sometimes illicitly produced due to the relative ease of synthesis and limited availability of chemical precursors.
The highest prevalence of illegal methamphetamine use occurs in parts of Asia, Oceania, and in the United States, where racemic methamphetamine, levomethamphetamine, and dextromethamphetamine are classified as schedule II controlled substances.