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How Long Does Meth Stay in the System (Urine, Blood, & More)

Meth is a dangerous stimulant drug that can cause intense euphoria, rapid addiction, high levels of physical energy and agitation, hallucinations, paranoia, sleeplessness for several days, and heart attacks, among many other side effects and potential problems. 

At first, meth abuse can make you feel good — more social, more awake, more enthusiastic — but this experience can turn into anxiousness, aggression, and fear. When the drug metabolizes out of your body, you will start to feel fatigued and depressed, which may trigger compulsive behavior to take more of the drug to feel better.

Although meth is a Schedule II substance in the United States — it is rarely prescribed to treat narcolepsy or attention-deficit hyperactivity disorder (ADHD) — it is most infamous as a potent substance of abuse that leads to physical harm and violence.

Meth abuse is on the rise again in the U.S. This drug ravaged primarily rural communities in the early 2000s, but after the U.S. Drug Enforcement Administration (DEA) cracked down on domestic meth producers, much of the drug’s production ceased, so fewer people struggling with addiction to the substance were able to acquire meth. However, super labs in Mexico have produced purer and cheaper batches of the drug and are shipping it across the border, leading to a rise in abuse of the drug once again.

As more people struggle with meth addiction, it is important to know that evidence-based treatment is available. Drug testing is an integral part of the treatment process, so it can help to understand how long meth remains in your body, how long it affects your brain, and how long it remains detectable in your blood, urine, and hair.

How Long Does Meth Stay in Your Body?

Meth’s effects begin soon after you ingest it, although the speed depends on how you abused the substance. Either intravenous or intramuscular injection leads to effects on the brain within 30 minutes while eating and digesting it leads to intoxication in two to three hours.

About 80 percent of the drug is bioavailable through these three routes of ingestion; about 79 percent is bioavailable when snorted, and 67 percent is bioavailable when smoked. With smoking and snorting meth, the drug hits peak effects in 2.5 hours. If meth is abused with alcohol, the drug’s impact will be magnified by the intoxicating drink.

The pH of your urine can also affect how long the drug remains in your system. More acidic urine leads to faster metabolization of meth.

If meth is injected, the half-life is 11.4 hours; if snorted, the half-life is 10.7 hours; and if smoked, the half-life is 10.7 hours. 

  • Urine: About 70 percent of meth comes out in urine within 24 hours after the dose is consumed. About 30 to 50 percent of that is still identifiable as the meth molecule, while 15 percent comes out as 4-hydroxymethamphetamine, and 10 percent appears as amphetamine. Meth will also accumulate in urine with repeated doses, so it is possible to detect meth abuse for up to seven days after a person has consumed as little as four doses of 10 mg each in one day. One report found that a single large dose, at 250 mg, led to detection of meth in the urine a week later 
  • Blood: It is possible to detect a single 10 mg dose of meth in the blood plasma for 36 to 48 hours. If meth is smoked, it gets into the bloodstream very fast, and it is detectable within minutes after ingestion since the drug is transferred into the blood through the alveoli in the lungs. Effects from this method, along with snorting, dissipate in about four hours, although the drug is still active in the brain. Eating meth metabolizes the drug more slowly, so it can be detected in blood tests for between 48 and 96 hours.

    Blood testing does not detect meth abuse, as well as urine testing, does. It is much more invasive, so it is not the preferred method of drug testing for this stimulant
  • Hair: Because of how long it takes hair to grow, this test is not a good method for detecting recent meth abuse; instead, it is used to determine if someone has ever abused the drug. A sample of hair that is 3 to 6 centimeters long can determine if someone has abused meth within the past 90 days (three months). Hair grows at a rate of about 1 centimeter per month, so it will take at least a month for meth abuse to be detected in a hair test. If a person started to abuse meth within the past one to three months, a hair test would be able to determine about when they started
  • Saliva: This is a rare approach to detecting meth abuse, but it can determine if someone has abused meth within the past one to three days. The stimulant can be detected in saliva within 10 minutes of it being ingested, and it typically remains detectable in the mouth for two days, on average   
  • Sweat: Some meth is secreted in sweat, but this form of testing is not reliable compared to others due to the low concentration of drugs secreted in the sweat. 

Two different kinds of drug tests — screening tests and confirming tests — can be used during rehabilitation to gather different information. Screening tests determine the presumptive presence or absence of a certain class of drugs in the specimen, so they can be run quickly because they are not aimed to detect all drugs that have been taken. This may be good for people who need prescription medications while they are in rehabilitation.

Confirmation tests provide more detailed information about the drugs in the blood and in what quantities they were found. This is correlated to how large the dose was and when the drug was taken.

Treatment Programs Often Use Drug Testing to Help You

detox and recovery

Regular drug testing is an important part of detox and recovery. In detox, an overseeing physician is likely using urine and blood tests to monitor your health as you withdraw from meth abuse. In rehabilitation, these tests are performed to ensure you have not relapsed and to get you appropriate help if you have.

You are less likely to undergo a blood test in rehabilitation because they are invasive, but urine tests may be required, especially if you are in an outpatient program. The tests help to confirm abstinence, allowing any health symptoms that come up to be diagnosed appropriately. For example, if you have mental health changes during your time in rehabilitation, it is important for your clinicians to know if this is related to your recovery, an underlying condition, or the effects of meth or a different drug.


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(July 2013). Methamphetamine. Drug Enforcement Administration (DEA), Office of Diversion Control, Drug & Chemical Evaluation Section. Retrieved November 2018 from

(August 15, 2018). Methamphetamine Toxicity. Medscape. Retrieved November 2018 from

(November 2003). The Bioavailability of Intranasal and Smoked Methamphetamine. Clinical Pharmacology & Therapeutics. Retrieved November 2018 from

(February 14, 2008). A Review of the Clinical Pharmacology of Methamphetamine. Addiction Review. Retrieved November 2018 from

How Long Does “Meth” Stay in Your System? (Methamphetamine). Mental Health Daily. Retrieved November 2018 from

Detection and Measurement of Drugs. National Highway Traffic Safety Administration (NHTSA). Retrieved November 2018 from

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