How Long Does Meth Stay in Your System?

Last Updated: May 26, 2023

Editorial Policy | Research Policy

Methamphetamine, commonly referred to as meth, can be prescribed for narcolepsy and attention-deficit/hyperactivity disorder (ADHD). Even though meth can be used medically, the drug is highly addictive and harmful.

Tolerance to meth builds quickly, so people will have to increase their dose to keep getting the same euphoric effects. When larger amounts of meth are consumed, the metabolites of the drug remain in a person’s body for longer periods.

So, how long does meth stay in your system? The answer depends on many factors. A single dose can typically be detected in urine for up to seven days. The length of time that meth remains in your system will primarily depend on how much meth has been used.

The purity of the meth also makes a difference. Crystal meth, a more purified and potent version of methamphetamine, triggers a longer-lasting high and stays in a person’s system longer than other forms of meth.

How Long Does Meth Last?

Meth causes peak effects within a few hours but takes a few days to leave the body completely. Once meth causes the desired effects (euphoria, energy or low appetite), the drug stays in the bloodstream even after these effects wear off.

The effects of meth last about eight hours after it has been absorbed by the body, regardless of how the drug is used. After eight hours, meth will still be present in the bloodstream but not at high enough levels to cause a noticeable effect.

How Meth Is Broken Down in the Body

Meth is mostly broken down in the liver. The liver creates proteins that break down meth by attaching other molecules to it or by changing its shape.

The products of metabolism (metabolites) are removed from the body through the intestines (stool) or the kidneys (urine). A small amount evaporates through the skin as sweat.

How Long Does It Take for Meth To Get Out of Your System

Several factors affect how long meth is detectable in a person’s system. Common detection factors include:

  • Amount used: Using even a small amount once is enough to create a positive result on any drug test for at least two days. Using larger amounts will extend the detection time.
  • Age: Older people may break down meth slower than younger people do and therefore prolong detection time, but no studies have proven this as a fact.
  • Overall health: Health issues like heart, liver and kidney problems will increase the length of time meth remains in the body.
  • Genetics: Your genes affect how the different proteins in your body are formed and how they work. This, in turn, influences how quickly meth is metabolized.
  • Other substances: The liver can only process a finite amount at one time. If meth is used with other substances, the liver will metabolize meth more slowly.

Meth Half-Life

A half-life is the amount of time it takes for the body to clear half of a drug out of the system. Meth’s half-life is about 10 hours and is the same regardless of how it is taken. The half-life of meth will vary for each individual based on their specific metabolism.

With a half-life of 10 hours, the amount of meth will decrease by half every ten hours. For example, if a person takes 30 mg of methamphetamine at 8:00 a.m., by 6:00 p.m. (10 hours later), half of the original amount (now 15 mg) will remain in the bloodstream. By 4:00 a.m. the next morning, 7.5 mg will remain in the bloodstream.

How Long Can Meth Be Detected on a Drug Test?

Meth detection times are quite long. Most meth drug screens can capture usage up to a week following meth’s last use. Meth drug tests can be conducted using a person’s blood, urine, saliva or hair. Each element has its own detection window.

How Long Does Meth Stay In Your Urine?

Urine drug tests are the most common type because they are inexpensive. Meth is detectable in urine for four to seven days after the last dose. Detection time may be higher for people who abused meth for a prolonged period of time.

How Long Does Meth Stay In Your Blood?

Meth shows up in the blood within hours after first use and can remain in the bloodstream for about two days. Meth blood tests are most commonly used by the police and in medical settings.

How Long Does Meth Stay In Your Saliva?

Saliva testing involves collecting a sample by swabbing the mouth or tongue with an absorbent material. Meth use can be detected in saliva for three days after the latest use.

How Long Does Meth Stay In Your Hair?

A meth hair test can detect meth use for up to 90 days in most tests, but more expensive tests can accurately detect meth use for up to 180 days.

When meth is in the bloodstream, it reaches the scalp and deposits into hair follicles. The hair then grows with traces of meth in it. Hair grows about 0.5 centimeters per month, and most tests take 1.5 cm of hair for testing.

Meth stays in the follicles only briefly until that portion of the follicle grows into the hair, where it stays until it is cut or falls out.

How Long Does Meth Stay In Your Breast Milk?

Because meth use is highly discouraged while breastfeeding, it is difficult to find people who use meth while still breastfeeding. While there is not much good data, research shows that meth is detectable for about 100 hours in breastmilk.

Umbilical Cord Testing for Meth

When babies are born, blood in the umbilical cord can be tested for substances like meth. While this method of testing is pretty unusual, it is essentially the same as a blood test, as the blood used to be part of the newborn’s circulation.

Meth used by a mother passes into the bloodstream of an unborn baby. The meth in the infant’s circulation that is present in umbilical cord testing will be detectable for the same time it would be in a normal blood test, about two days.

False Positives for Meth

False positives for meth are relatively common because the drug’s molecular structure is simple. When a drug test “looks” for meth, it may accidentally find a molecule with a similar shape, which can cause a false positive.

Meth false positive causes due to a medication can include:

  • Allergy medications (chlorpheniramine, brompheniramine, pheniramine)
  • Antidepressants (bupropion, trazodone, selegiline, fluoxetine, tricyclic antidepressants)
  • Decongestants (phenylephrine, ephedrine)
  • DMAA, an energy supplement
  • Phentermine, an appetite suppressor

When a drug test comes back positive, the person tested will be asked about any other medications they are taking to rule out a false positive.

The sample is then sent to another lab for a test called gas chromatography-mass spectrometry. This type of analysis can confirm the sample with almost 100% accuracy, so a false positive drug screen will then be verified.

Finding Help for Meth Addiction in Washington

Meth addiction is dangerous, leading to serious long-term health problems. Additionally, an addiction to meth can lead to employment problems, as it decreases your safety at work and could lead to losing your job if you are found to be using.

The Recovery Village Ridgefield offers professional meth addiction treatment, both for the detox and for longer-term rehab, to help maintain sobriety after withdrawal is over. We are an in-network provider for a range of insurance companies, including Aetna, Cigna and America’s Choice. Learn more about the insurance we accept by visiting our insurance page.

If you or a loved one struggles with meth addiction, The Recovery Village Ridgefield can help. Call today to speak with a representative who can help you find the treatment best suited for your needs.


Our Recovery Advocates are ready to answer your questions about addiction treatment and help you start your recovery.

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