Meth users are often seduced by the intensity of the initial high, a high many say is unlike anything they have experienced before. Almost immediately, users build up a tolerance for the drug, causing them to vary the quantity, frequency, or method of intake in an effort to recreate that first experience. This incites a form of binging known as a "run," sometimes using as much as a gram of the drug every 2 to 3 hours for several days until the drug is either gone or the user is too disoriented to continue.
Even with sustained low-level usage, a person will often begin to experience symptoms such as drug craving, extreme weight loss, loss of muscle tone, and tooth decay, along with withdrawal-related depression and other symptoms. High doses can elevate body temperature to dangerous, sometimes lethal levels, as well as cause convulsions.
As tolerance sets in, the user will often begin to use Meth more frequently in order to avoid withdrawal symptoms. Although there are no physical manifestations of withdrawal syndrome when Meth usage is stopped, several symptoms including depression, anxiety, fatigue, paranoia, extreme aggression, and an intense craving for the drug may occur.
Long-term Meth abuse may result in many damaging effects, including: violent behavior, anxiety, confusion, insomnia, paranoia, auditory hallucinations, mood disturbances, and delusions (for example, the sensation of insects crawling on the skin). This chronic use frequently leads to symptoms such as: neurotoxicity (brain damage), respiratory problems, irregular heartbeat, and irreversible damage to blood vessels in the brain—producing strokes, heart and kidney damage, cardiovascular collapse, and death.