How Long Does Meth Stay In Your System?

Last Updated: December 16, 2020

Authored by Isaak Stotts, LP

Reviewed by Michael Espelin APRN

Methamphetamine is a drug with an active stimulant potential. Therefore, this makes it an addictive, illegal drug, which triggers the elevation of dopamine levels. Those addicted to this substance need immediate treatment.
Right after the substance enters the person’s bloodstream, the body starts to metabolize it. Continually, some of the methamphetamines are then quickly converted into amphetamine. The liver and kidney then process methamphetamine and amphetamine. The drug will finally make its way to the urinary tract for excretion from the body.

Crystal Methamphetamine Mechanism Of Action

Meth is a psychostimulant. A synapse is a gap between two neurons. The neuron present before this gap is called the presynaptic neuron, and the one after it is called the postsynaptic neuron. When the presynaptic neuron present in the brain’s reward circuit releases dopamine in response to a reward encounter, it attaches to the dopamine receptors on the postsynaptic neuron. This creates a feeling of pleasure. The excess dopamine is reabsorbed into the presynaptic neuron.

When an individual takes methamphetamine, two things happen. First, the dopamine cannot be reabsorbed by the presynaptic neuron. Second, more dopamine is released by the presynaptic neuron. This causes the ‘high’ experienced by the users. Alertness and energy are increased paired with a feeling of euphoria, increased heart rate, and blood pressure. The prolonged use of this drug can reduce the natural production of dopamine. This makes the individuals depressed and low unless they take the drug, leading to addiction.

How Is Methamphetamine Metabolized In the Body?

Although amphetamines can cross the blood-brain barrier, the additional methyl group in methamphetamine makes it more lipid-soluble and gives it an increased permeability through this barrier. It is broken down in the liver by CYP2D6 enzyme to form amphetamine and 4-hydroxymethamphetamine. This makes up around half of the plasma clearance.

Crystal meth drug.

The kidney filters it out as methamphetamine and amphetamine in various combinations of percentages based on the route of intake. The rate at which it is excreted via urine depends on the urine pH.

Crystal Meth Half-Life

Crystal meth is a white crystal or powdered form of methamphetamine. Some ways of how people use it can range from injecting, snorting, and smoking. Performing urine, blood, saliva, and a hair drug test for meth can show various time spans of the drug’s presence in one’s system.

Urine drug test on meth.

So, how long does meth stay in your system? It is hard to determine the precise duration of its presence in one’s system since factors that influence the speed of methamphetamine metabolism are numerous. However, some approximate calculations suggest that the half-life of meth is 12-34 hours in the blood. Its effects can last between 8-24 hours, after which withdrawal symptoms appear. Furthermore, the drug takes between 12 to 34 hours for there to be a reduction of concentration in the blood. Sometimes it can take up to 10 days for methamphetamine to entirely leave the body.

How Long Does Meth Stay In Your Blood?

Blood drug tests for meth are traditional ways of testing that work great in detecting new consumption. They can be effective as soon as 2 hours after use. As meth half-life is around 12 hours, the time Ice needs to be reduced by half will be 12-34 hours. Blood tests can identify the substance for up to 1-3 days, while in dense users – up to 10 days.

How Long Does Meth Stay In Your Urine?

Urine tests are one of the most used forms of drug testing. When meth leaves the system, it is cleared by the kidneys, and an enormous amount of metabolites can show in one’s urine. Urinalysis can detect methamphetamine 2-6 hours after use and for up to 3-5 days.

How Long Does Meth Stay In Your Saliva & Sweat?

Our bodies are full of fluids. Therefore, methamphetamine can show up in one’s saliva and sweat. Saliva tests are ideal for home use or occasions when the tester shouldn’t invade the user’s personal space too much. Swab tests are perfect for 5-10 minutes after use and can detect meth for up to 72 hours (sometimes even four days). Note that the saliva contains more of the drug, not its metabolites.

How Long Does It Stay In Your Hair?

As our body is one whole system, methamphetamine can be found in the hair as well. No matter how much one washes or cuts the hair, tests can detect crystal meth for up to 90 days after the last dose.

Factors That Influence the Period Of Methamphetamine Detection

Methamphetamine will leave the system only after the body processes it, and it takes time. Several factors contribute to the length of time the substance is detectable in the system.

They Are:

  • Age
  • Weight
  • General health
  • Genetics
  • One’s frequency of drug use
  • The amount of one’s last dose
  • The functionality of one’s kidneys and liver
  • The type of test (urine, blood, hair, saliva) used to detect the drug

Generally, the longer a person abuses meth and the stronger the addiction, the longer it will take for methamphetamine to leave the body. Moreover, people abusing methamphetamine for long periods of time are likely to have bad general health, which will prolong this process. If the addiction has taken over, it is advised to seek treatment for meth addiction.

False-Positive Result

A false-positive result occurs when the test shows the drug metabolites’ presence in the system when you haven’t taken it. There are several medications that can cause a false-positive result in a methamphetamine drug test:

  • Antidepressants ( tricyclic medicines, quetiapine, and bupropion)
  • Certain antihistamines, nasal inhalers, or cold medicines
  • Metformin (used to treat type 2 diabetes)
  • Ritalin
  • Labetalol 

The detection time for methamphetamine can vary depending on various factors. Crystal meth use is dangerous to one’s health; therefore, those suffering from addiction are recommended to immediately seek medical help. This can help to avoid the life-threatening consequences of drug abuse. The treatment for addiction to methamphetamine and recovery is possible. Medical treatment will help go through the withdrawal process safer. After staging the intervention, the recovery process starts in one of the drug rehabilitation centers specialized in treating crystal meth abuse.


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Published on: May 3rd, 2017

Updated on: December 16th, 2020

About Author

Isaak Stotts, LP

Isaak Stotts is an in-house medical writer in AddictionResource. Isaak learned addiction psychology at Aspen University and got a Master's Degree in Arts in Psychology and Addiction Counseling. After graduation, he became a substance abuse counselor, providing individual, group, and family counseling for those who strive to achieve and maintain sobriety and recovery goals.

Medically Reviewed by

Michael Espelin APRN

8 years of nursing experience in wide variety of behavioral and addition settings that include adult inpatient and outpatient mental health services with substance use disorders, and geriatric long-term care and hospice care.  He has a particular interest in psychopharmacology, nutritional psychiatry, and alternative treatment options involving particular vitamins, dietary supplements, and administering auricular acupuncture.