Determining How Long Does Meth Stay In Your System

medical specimen collection bottle in gloved hand

How Long Does Meth Stay In Your System: Methamphetamine (street names ice, crystal meth, crank or meth) is a powerful nervous system stimulant smoked, injected or snorted by abusers. Chemically classified as an amphetamine, methamphetamine is quickly absorbed by the body and achieves peak plasma levels within three to six hours. Injecting meth reduces this time to two to four hours, meaning meth addicts who inject the drug into their veins feel its effects quicker and more powerfully than when snorted or smoked.

Metabolizing Methamphetamine

Due to its ability to dissolve rapidly in body lipids and fats, methamphetamine moves easily over the blood-brain barrier, targeting the serotonergic and dopaminergic transmitter systems. Chronic meth users may also suffer irreversible damage to neurons and nerve terminals that causes serious cognitive problems.

Understanding the pH Factor

How quickly the kidneys excrete methamphetamine is heavily dependent on the pH level of the user’s urine.

Health problems common to meth abusers that could increase urine pH include;

  • malnutrition
  • dehydration
  • diarrhea
  • diabetes

Higher urine pH levels cannot excrete meth as efficiently as urine with normal or lower pH levels.

When injected, methamphetamine levels in urine reaches 45 percent while seven percent will test as amphetamine. Snorting or taking meth orally results in urine containing 30 to 54 percent methamphetamine and 10 to 23 percent amphetamine.

Length of Time Methamphetamine Can Remain Detectable

Determining how long does meth stay in your system depends on a variety of factors, including;

  • age
  • gender
  • overall health
  • dose ingested recently
  • how long the person has been a user
  • how it was taken

How Long Does Meth Stay In Your System – Urine

Positive results in a urine test generally will indicate use within a  1 to 4 day range. For heavy chronic use, it could be as much as a week, or longer. The rate of meth excretion into the urine is primarily influenced by how much pH is on the urine.

The answer most people consider a fairly good number, for a urine type drug test, is at least 72 hours . It could be longer.

  • The truthful, most honest answer is…there is no exact answer, only a possible range

Half-life of methamphetamine is about 10 hours, depending on body chemistry, metabolism and current health condition of the user. That means approximately 50% is metabolized every 10 hours. This is important because it is fair way to measure when you can expect to be “clean”.

  • Smoked meth can remain detectable in the bloodstream for up to 48 hours
  • Snorting meth can remain in the blood for as long as four days
  • People injecting meth may test clean within two to three days
  • Methamphetamine remains detectable in urine up to 70 hours
  • Daily users of meth may fail drug test even if they stop using weeks before testing
  • Concentrations of methamphetamine are higher in saliva than blood plasma

How Long Does Meth Stay In Your System
Occasional users of methamphetamine (those using meth once a month or less) will definitely test positive for meth if they are tested within 24 hours of snorting or injecting the drug. Depending on a person’s metabolism, health, age and other factors, they may test negative only one or two days after using.

People using meth once or twice a week tend to retain more amphetamine molecules in their soft tissues. Since the half life of meth is about 10 hours, elimination of 50 percent of meth from the body will take at least 12+ hours. Also, methamphetamine may be detected through urine, blood, hair and saliva tests for 96 hours, if you use once or twice a week.

Daily users of meth are the most likely to fail drug testing even if they stop using several weeks prior to taking a test. Tolerance to meth means abusers must take more of the drug to feel the same effects they once felt when taking less meth. In fact, it may take daily users (addicts) of methamphetamine more than four or five days of strict abstinence before they would pass a test. Even then, this window of time should not be relied on for passing a meth test, especially if it is a hair follicle test.

The most common way meth drug tests are administered is by performing an immunoassay test on urine samples. Immunoassays detect substances in body fluids utilizing immunological reactions to certain antibodies. Results of an immunoassay meth test are deemed negative, positive or quantitative (how much of the drug is found in the fluid). If a meth drug test is positive, a sample from the original specimen may be retested using mass spectrometry/gas chromatography for validation, if the person appeals the positive result of the immunoassay test.

Detecting Meth in Hair Samples

Methamphetamine can be detected in hair samples for as long as four or five months following cessation of using the drug. Compared to urine testing for meth, hair follicle tests are more effective at detecting low-level use of meth, opioids and cocaine.

Pass a Meth Test

Drinking lots of water or taking herbal supplements that claim to “clean” out your system are ineffective for removing traces of methamphetamine and amphetamine. The best way to pass a blood or urine drug test is to stop using the drug at least six months before taking the test. Hair follicle tests, however, can detect signs of drug use for several years after a user last took an illegal drug.

Consequences of Methamphetamine Abuse

Methamphetamine is more addictive than opioids and cocaine because it directly disrupts neurotransmitter systems involved in reward, pleasure and motivation. In addition, meth also exerts more damage to the brain than other drugs, with an extended period of neural repair needed following detoxification and rehabilitation. Heavy meth abusers may suffer symptoms of psychosis for the rest of their lives, including severe memory loss, halting speech and attention deficit disorder.


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