How Long Does Methamphetamine Stay in Your System?

Determining exactly how long meth is detectable in the body depends on many variables, including which kind drug test is being used. Methamphetamine—also known as Desoxyn, crank, crystal, glass, ice, and speed—can be detected for a shorter time with some tests, but can be visible for up to three months in other tests.

The following is an estimated range of times, or detection windows, during which meth can be detected by various testing methods:

• Urine Test: 1 to 4 days, but may be detectable for up to a week after heavy chronic use
• Blood Test: 1 to 3 days
• Saliva Test: 1 to 4 days
• Hair Follicle Test: Up to 90 days.

The timetable for detecting meth in the system is also dependent upon each individual's metabolism, body mass, age, hydration level, physical activity, health conditions and other factors.

Methamphetamine is metabolized by a liver enzyme and is excreted by the kidneys in urine. It is metabolized to amphetamine, p-OH-amphetamine, and norephedrine.

When taken orally, concentrations of methamphetamine peak in the bloodstream between 2.6 and 3.6 hours and the amphetamine metabolite peaks at 12 hours. If meth is taken intravenously, the elimination half-life is a little longer, about 12.2 hours.

The effects of methamphetamine begin rapidly after intravenous use or when it is smoked. The main effects last from four to eight hours with residual effects lasting up to 12 hours. Therefore, amphetamine is detectable in drug tests long after the user no longer feels the effects.

The effects of methamphetamine are also much different at prescribed therapeutic doses than those dosages usually used by meth abusers. Doses of 10 to 30 milligrams can improve reaction time, relief fatigue, improve cognitive function testing, increase subjective feelings of alertness, increase time estimation, and increase euphoria.

However, at larger dosages meth can cause agitation, inattention, restlessness, inability to focus attention on divided attention tasks, motor excitation, increased reaction time, time distortion, depressed reflexes, poor balance and coordination, and inability to follow directions.

Many states have passed zero tolerance laws for driving while under the influence of methamphetamine. In those states, if a blood test shows any amount of meth at all, you can be charged with driving under the influence.

Because methamphetamine remains in the system long after the effects of the drug wear off, you might feel like you are okay to drive, but can still run the risk of being charged with drugged driving if any meth shows up in a blood or urine test.

According to the National Highway Traffic Safety Administration, drivers who are under the influence of methamphetamine display a wide variety of behaviors including "speeding, lane travel, erratic driving, accidents, nervousness, rapid and non-stop speech, unintelligible speech, disorientation, agitation, staggering and awkward movements, irrational or violent behavior, and unconsciousness."

In the 101 cases reviewed by the NHTSA in which meth was the only drug detected, impairment was attributed to "distraction, disorientation, motor excitation, hyperactive reflexes, general cognitive impairment, or withdrawal, fatigue, and hypersomnolence."

Meth users may think that doing methamphetamine can reverse some of the impairment effects of alcohol. That's because meth may restore alcohol-induced impairment in simple repetitive tasks of short duration.

However, NHTSA research has uncovered no restoration of alcohol-induced deficits of balance and steadiness. Overall, research indicates that methamphetamine is more likely to increase the impairing effects of alcohol.

Another reason that it is important to be aware of how long meth remains in your body is the fact that it is highly addictive. If you take more while some of the drug is still in your system you increase the risk of becoming dependent.