How Long Does Methamphetamine (Meth) Stay in Your System?

Methamphetamine in Your Blood, Urine, Hair, & Saliva

In This Article

Methamphetamine, also known as Desoxyn, meth, crank, crystal, glass, ice, and speed, is a stimulant drug that speeds up the body’s systems. After marijuana, meth is the second most popular illicit drug in the world. Methamphetamine is classified as a Schedule II drug in the U.S., meaning that it's considered a drug with a high potential for misuse, with use potentially leading to severe psychological or physical dependence. Though most often used illicitly as a recreational drug, it is also currently available in prescription form as Desoxyn, which is used for treating ADHD and the short-term treatment of obesity.

Determining exactly how long meth is detectable in the body depends on many variables, including the type of test used, the method of use, and a person's unique physical characteristics. Methamphetamine can be detected for a shorter period of time with some tests but can be visible for up to three months in others.

How long meth stays in your system
Verywell / Jessica Olah

How Long Does It Take to Feel the Effects?

The effects of methamphetamine begin rapidly after intravenous use or when it is smoked. The primary effects last from four to eight hours, with residual effects lasting up to 12 hours. Therefore, amphetamine (a methamphetamine metabolite) is detectable in drug tests long after the person feels back to normal.

The effects of methamphetamine vary widely between prescribed therapeutic doses compared to dosages usually used by people who misuse meth. Prescription doses of 10mg to 30mg can improve reaction time, relieve fatigue, improve cognitive function testing, increase subjective feelings of alertness, increase time estimation, and increase euphoria.

However, a larger dose of meth can cause the following effects:

  • Agitation
  • Inattention
  • Restlessness
  • Inability to focus attention on divided attention tasks
  • Motor excitation
  • Increased reaction time
  • Time distortion
  • Depressed reflexes
  • Poor balance and coordination
  • Inability to follow directions

Driving Concerns

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
  • Awkward movements
  • Irrational or violent behavior, and unconsciousness

In the 101 cases reviewed by 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."

How Long Does Meth Last?

The half-life of methamphetamine is an average of 10 hours. This means it takes about 10 hours for half of the ingested dose to be metabolized and eliminated from the bloodstream. 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 at about 12.2 hours.

Methamphetamine is metabolized by a liver enzyme and is excreted by the kidneys in urine. It is metabolized (or broken down) into amphetamine, p-OH-amphetamine, and norephedrine.

Various testing methods have different estimated ranges of times or detection windows, during which meth can be picked up after a person has taken the drug.

Urine

Meth is typically detectable in urine for one to four days but may be detectable for up to a week after heavy, chronic use. A urine test typically shows a higher concentration of meth than other drug tests because the drug's metabolites are eliminated through urine.

Blood

Blood tests can detect meth most quickly after it's been used, typically one to three days after last use.

Saliva

Meth can be detected in saliva for one to four days after the last use.

Hair

A hair follicle test can detect meth in your system for up to 90 days.

False Positive Testing

Taking metformin (sold as Fortamet, Glucophage, Glumteza, Glucophage XR, and Riomet) used to treat type 2 diabetes, can result in a positive test for methamphetamine. Certain antihistamines, nasal inhalers, cold medicines, and antidepressants can also produce false positives.

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 OK 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.

Factors That Affect Detection Time

The timetable for detecting methamphetamine in the human body depends on the individual's health, metabolism, age, physical activity, and frequency of use, making it difficult to determine how long meth will show up on a drug test.

Overall Health

Your overall health, including liver and kidney function, can play a role in how quickly meth is processed and cleared from your body.

Frequency of Use

If you use meth one time, it might be detectable for only a short period of time, whereas heavy or very frequent use can cause concentrations in the system that can be detected for longer periods of time.

Metabolic Rate

People with a high metabolism tend to process and excrete methamphetamine more quickly than those with a slower metabolism. Age, activity level, and overall health can all play a role in your metabolic rate.

Smoking vs. Injecting

Whether you take the drug orally or intravenously can impact detection time. For example, if you smoke or snort meth, it will stay in the body for a shorter amount of time than if you inject the drug.

How to Get Heroin Out of Your System

There are plenty of false claims and myths when it comes to how to pass a drug test. Specifically, some meth users have attempted to drink "baking soda bombs," which is a mixture of water, bleach, and baking soda that is said to mask the presence of methamphetamine in their urine. There is no proven research that this works, and further, you're taking an enormous health risk when you ingest any amount of bleach.

The only way to get meth out of your system is to stop using the drug. Staying healthy by getting regular exercise and drinking plenty of water may also help you metabolize the substance more quickly.

Symptoms of Overdose

One of the main reasons to be aware of how long meth remains in the system is the risk of overdose. Here are some symptoms of a meth overdose:

  • Difficulty breathing
  • Chest pain
  • Irregular heartbeat
  • Heart attack
  • Stroke
  • Seizures
  • Severe agitation
  • Paranoia
  • Extremely high body temperature
  • Kidney damage or failure

Some of these symptoms can be life-threatening, so it is important to seek professional medical help right away if you suspect that you or a loved one may be experiencing a methamphetamine overdose.

Meth and Alcohol

Some believe that 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.

The combination can also increase the risk of alcohol poisoning since people do not realize how much they’ve had to drink. In addition, heart rate is raised more than using meth alone, increasing the risk of future heart disease with long-term use.

Getting Help

If you're concerned about having too much meth in your system or testing positive for the drug, it's likely time to seek help or consult your doctor. If you use meth heavily and/or regularly, it's best to detox from the drug under the guidance of a medical professional who can guide you safely through the withdrawal and treatment process.

Twenty four hours after you stop using meth, you can expect to experience symptoms of withdrawal, which can range from mild to severe, depending on the frequency of use and dependency. Some common signs and symptoms of meth withdrawal include:

  • Anxiety
  • Fatigue and sleepiness
  • Depression
  • Psychosis
  • Cravings
  • Increased appetite

If you or someone you love wants to quit using meth, there are steps you can take to get through the withdrawal process and succeed in your recovery.

Start by talking to your doctor for advice and assistance, or contact the Substance Abuse and Mental Health Services Administration (SAMHSA) at 1-800-662-4357. They also have a free, online tool to find treatment options in your area.

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Article Sources

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institute on Drug Abuse. Methamphetamine. Updated April 2019.

  2. Couper FJ, Logan BK. Drugs and Human Performance Fact Sheets. National Highway Traffic Safety Administration. April 2014 (Revised).

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