When a person takes meth, it changes the brain’s natural reward system and triggers the release of dopamine. This produces the initial high, which lasts about 14 hours. Then, the meth user experiences a comedown, when they experience depressed and low moods. Often, this comes with itching and other physical symptoms as well. Typically, the meth addict will use the drug again to feel better and start the cycle all over again.
When someone snorts or smokes meth, it enters the bloodstream quickly and produces an immediate effect. This is different from swallowing a pill, which has to pass through the digestive system before reaching the brain. The first phase of being high on meth is the rush, which can include feeling exhilarated, aroused, and confident. It also causes heart rate to speed up and increases blood pressure. Other feelings might include paranoia, euphoria, disinhibition, and aggression.
The body breaks down meth and eliminates it through urine, but some of the drug’s metabolites can remain in the kidneys for long periods of time. This means that meth can still be detected in a urine test up to three days after the last dose. Other factors that can affect how long meth stays in the system include: a person’s metabolism, their overall health, and their age.
Frequent meth use and higher dosages can also cause the drug to build up in the system, extending its detection times. It can also take longer to clear the body of meth if a person is taking other medications or has preexisting medical conditions.