Methamphetamine Abuse

Drug Effects

The sensation acquired after using methamphetamine varies with the route of administration. Effects are felt most rapidly with injection, and more slowly with inhalation. Ingestion of pills provides the most delayed high. A “rush” of euphoria, an intensely pleasurable feeling attained soon after taking methamphetamine, is unique to injection and inhalation.

Pharmacologically, methamphetamine acts by affecting the amount and effects of monoamine neurotransmitters, particularly norepinephrine, dopamine, and serotonin, in the central nervous system. The drug acts as a very potent stimulant, causing euphoria, enhancing alertness, improving attention, and increasing libido.

It is also not uncommon for methamphetamine users to become violent while under the influence of the drug. “Coming down” off higher doses of the drug shows opposite effects, including fatigue, difficulty concentrating, and often, severe depression.

A variety of physiological changes also occur. There are increases in heart rate, blood pressure, core temperature, and respiratory rate, and substantial constriction of blood vessels occurs. Side effects, often present at low doses but especially prominent at higher doses, include cardiac arrhythmia, hyperthermia, stomach cramping, trunk and limb muscle tremor, repetitive behavior, jaw clenching and teeth grinding, anxiety, aggression, paranoia, and insomnia. In rare cases, cardiac abnormalities and stroke can occur and are potentially fatal.

Animal studies, most of which have involved rats, have shown that after recurrent methamphetamine usage, anatomic changes occur in the brain that compromise the integrity of dopamine and serotonin systems. These findings suggest that long-term use of the drug, or perhaps even single large administrations or binges, may produce lasting changes in central nervous system functioning. However, very few human studies have been performed, although those that do exist are consistent with the data obtained from animals.

What is known is that although the single-dose effects of methamphetamine include enhanced concentration and memory and psychomotor performance, long-term use leads to global cognitive impairment in these same functions. Weight loss, erectile dysfunction, and rapid and severe tooth decay, a phenomenon known as “meth mouth,” are other prominent side effects associated with chronic use. With time, psychological dependence can develop as a methamphetamine user experiences slow thinking and depression when not taking the drug, requiring him or her to use more methamphetamine to maintain previous levels of functioning.

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