How Long Does Meth Stay In Your System For a Drug Test

Dr. Kim Langdon Cull MD

This article was reviewed and approved by Dr. Kim Langdon Cull MD

How long does crystal meth stay in your system for a drug test? The most honest answer is there is no exact answer, only a possible range. Positive results in a urine test generally will indicate use within a 1 to 4 day period. However, it could be as much as a week or longer for heavy chronic users, because the pH of the urine primarily influences the rate of excretion rate into the urine.

How quickly the kidneys excrete the drug depends on the user’s urine pH level. Higher urine pH levels (alkaline) cannot excrete it as efficiently as urine with average or lower (acidic) levels.

  • Most people consider a reasonably good number for passing a urine type drug test is 72 hours of total abstinence.
  • Drinking lots of water or taking herbal supplements that claim to “clean” out your system are generally ineffective for removing all traces. 

Understanding the details of these drug tests is essential for employers and employees alike.

  • Chemically classified as an amphetamine, methamphetamine achieves peak plasma levels within three to six hours.
  • Injecting reduces this time to two to four hours, meaning addicts who inject the drug into their veins feel its effects quicker and more powerfully than when snorted or smoked.
  • When meth is injected, pH levels in the urine reach forty-five percent, and seven percent will show up as amphetamine. 
  • People who are snorting or orally taking this drug results in urine containing 30 to 54 percent methamphetamine and 10 to 23 percent amphetamine. 

Health problems that could increase urine pH include: 

  • Malnutrition
  • Dehydration
  • Diarrhea
  • Diabetes


Half-life is the amount of time it takes for the human body to process 50% of a drug.

  • The half-life is approximately 10 hours.

Therefore, the body breaks down and removes about 50% every 10 hours. It is essential because it is fair to measure when you expect to be “clean.” Then, another 50% of the remaining passes in the next 10 hours until levels become very low. 


Approximate amount of time this drug is detectable depends on which type of test and range of detection or cutoff levels. 

  • This amount of time depends on the user’s body chemistry, metabolism, and current health condition.
  • Smoked, it can remain detectable in the bloodstream for up to 48 hours.
  • Snorting it can stay in the blood for as long as four days.
  • People injecting it may test clean within two to three days.
  • It remains detectable in urine for up to 70 hours.
  • Daily users may fail a drug test even if they stop using weeks before testing.
  • Concentrations are higher in saliva than blood plasma.

Occasional users (those using this drug once a month or less) will test positive within 24 hours of snorting or injecting the drug. However, depending on a person’s metabolism, health, age, and other factors, they may test negative only one or two days after use. 

  • People using it once or twice a week tend to retain more molecules in their soft tissues. 
  • Also, it may be detected through urine, blood, hair, and saliva tests for 96 hours if used once or twice a week. 
  • Daily users are the most likely to fail drug testing even if they stop using several weeks before taking a test. 
  • Tolerance means abusers must take more of the drug to feel the same effects they once felt when taking less of it. As a result, it may take daily users (addicts) more than four or five days of strict abstinence before passing a test. 
  • Even then, this window of time should not be relied on for passing a test, especially if it is a hair follicle test. 

Special type of test

An immunoassay type urine test detects substances in body fluids utilizing immunological reactions to:

  • specific antibodies
  • If a drug test is positive, a sample from the original specimen may use mass spectrometry/gas chromatography to validate if the person appeals to the positive results. 

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

  • Age 
  • Gender
  • health 
  • Metabolism 
  • Dose recently
  • How long a user 
  • Method of use

Hair testing

It can be detected in hair samples for four or five months following the drug’s cessation. Compared to urine testing for this drug, hair follicle tests detect low levels of this drug as well as opioids and cocaine use. 

However, hair follicle tests can detect drug use signs for several years after a user last took an illegal drug, depending on the length of the hair. 


Meth is a white, bitter-tasting powder. It looks like glass fragments or shiny, bluish-white rocks. It is best known as crystal meth. It can be smoked, injected, or snorted. 


It affects the central nervous system and is a schedule II stimulant, making it legally available through a doctor’s prescription but rare. The precursor drug is an amphetamine. Short-term use for weight-loss treatments and attention deficit hyperactivity disorder (ADHD) treatment. 

  • Users have reported addiction after only one use. 

It is a potent central nervous stimulant due to its ability to dissolve rapidly in the body’s lipids and fats, allowing it to move effortlessly over the blood-brain barrier.

Thus, it targets the serotonergic and dopaminergic transmitter systems. 

The production uses pseudoephedrine, the active ingredient in over-the-counter cold medicines like Sudafed. Because of this, it has become harder and harder to purchase Sudafed in any substantial quantity. 

It causes increased physical activity and talkativeness, decreased appetite, and pleasurable well-being or euphoria. It creates a rush (strong feeling) of confidence and energy. It causes a strong desire to continue its use and is the reason for its addictive tendencies. 

Because it is a highly addictive drug when people stop taking it, withdrawal symptoms often occur, including;

  • anxiety
  • fatigue
  • severe depression
  • psychosis
  • intense drug cravings

In addition, stroke, heart attack, or organ problems—such as kidney failure—caused by overheating are causes of an overdose. Chronic users may also suffer irreversible damage to neurons and nerve terminals that causes severe cognitive problems. Death can be a result of these powerful effects. Long Term Use Can Cause Permanent Damage.

Long term effects may include: 

  • Increased risk of contracting infectious diseases 
  •  May worsen the progression of HIV/AIDS and its consequences. 
  •  Severe dental problems (“meth mouth”) 
  •  Anxiety, confusion, paranoia 
  •  Hallucinations and addiction 

It is more addictive than opioids and cocaine because it directly disrupts neurotransmitter systems involved in reward, pleasure, and motivation.

It also exerts more damage to the brain than other drugs, with an extended period of neural repair needed following detoxification and rehabilitation.

Heavy abusers may suffer symptoms of psychosis for the rest of their lives, including severe memory loss, halting speech, and attention deficit disorder.

The best way to insure passing a blood or urine drug test is to stop using the drug at least six months before taking the test.