Methamphetamine Recreational Use: Effects.

Physical:

Physical effects can include anorexia, hyperactivity, dilated pupils, flushed skin, excessive sweating, restlessness, dry mouth and bruxism (leading to "meth mouth"), headache, accelerated heartbeat, slowed heartbeat, irregular heartbeat, rapid breathing, high blood pressure, low blood pressure, high body temperature, diarrhea, constipation, blurred vision, dizziness, twitching, insomnia, numbness, palpitations, tremors, dry and/or itchy skin, acne, pallor, and – with chronic and/or high doses – convulsions,heart attack, stroke & death^.

Psychological:

Psychological effects can include euphoria, anxiety, increased libido, alertness, concentration, increased energy, increased self-esteem, self-confidence, sociability, irritability, aggressiveness, psychosomatic disorders, psychomotor agitation, dermatillomania (compulsive skin picking), hair pulling, delusions of grandiosity, hallucinations, excessive feelings of power and invincibility, repetitive and obsessive behaviors, paranoia, and – with chronic use and/or high doses – amphetamine psychosis^.

Withdrawal:

Withdrawal symptoms of methamphetamine primarily consist of fatigue, depression, and increased appetite. Symptoms may last for days with occasional use and weeks or months with chronic use, with severity dependent on the length of time and the amount of methamphetamine used. Withdrawal symptoms may also include anxiety, irritability, headaches, agitation, restlessness, excessive sleeping, vivid or lucid dreams, deep REM sleep, and suicidal ideation.

Long-term:

Methamphetamine use has a high association with depression and suicide as well as serious heart disease, amphetamine psychosis, anxiety, and violent behaviors. Methamphetamine also has a very high addiction risk. Unlike cocaine and amphetamine, methamphetamine is directly neurotoxic to midbrain dopamine neurons. Moreover, methamphetamine use is associated with an increased risk of Parkinson's disease due to the fact that uncontrolled dopamine effluxion is neurotoxic^. Long-term dopamine upregulation occurring as a result of methamphetamine abuse can also cause neurotoxicity, which is believed to be responsible for causing persisting cognitive deficits, such as memory loss, impaired attention, and decreased executive function. Similar to the neurotoxic effects on the dopamine system, methamphetamine can also result in neurotoxicity to serotonergic neurons.

As a result of methamphetamine-induced neurotoxicity to dopaminergic neurons, chronic use may also lead to post acute withdrawals which persist beyond the withdrawal period for months, and even up to a year. A study performed on female Japanese prison inmates suffering from methamphetamine addiction showed that 49% experienced "flashbacks" afterward and 21% experienced a psychosis resembling schizophrenia which persisted for longer than six months post-methamphetamine use; this amphetamine psychosis could be resistant to traditional treatment. Other studies in Japan show that those who experience methamphetamine-induced psychosis are much more likely to experience psychotic symptoms again if they use methamphetamine. In addition to psychological harm, physical harm – primarily consisting of cardiovascular damage – may occur with chronic use or acute overdose^.

Tolerance:

As with other amphetamines, tolerance to methamphetamine is not completely understood but is known to be sufficiently complex that it cannot be explained by any single mechanism. The extent of tolerance and the rate at which it develops vary widely between individuals, and even within one person. It is highly dependent on dosage, duration of use, and frequency of administration. Tolerance to the awakening effect of amphetamines does not readily develop, making them suitable for the treatment of narcolepsy. Short-term tolerance can be caused by depleted levels of neurotransmitters within the synaptic vesicles available for release into the synaptic cleft following subsequent reuse (tachyphylaxis). Short-term tolerance typically lasts until neurotransmitter levels are fully replenished; because of the toxic effects on dopaminergic neurons, this can be greater than 2–3 days. Prolonged overstimulation of dopamine receptors caused by methamphetamine may eventually cause the receptors to downregulate in order to compensate for increased levels of dopamine within the synaptic cleft. To compensate, larger quantities of the drug are needed in order to achieve the same level of effects. Reverse tolerance or sensitization can also occur. The effect is well established, but the mechanism is not well understood.