How Long Does Methamphetamine (Meth) Stay in Your System?

Methamphetamine, also known under the brand name Desoxyn or street names meth, crank, crystal, glass, ice, and speed, is a stimulant drug that speeds up the body’s systems. After marijuana, meth is the second most popular illicit drug in the world.

Methamphetamine is classified as a Schedule II drug in the United States, meaning that it's considered a drug with a high potential for misuse, with use potentially leading to severe psychological or physical dependence.

Though most often used illicitly as a recreational drug, it is also available in prescription form as Desoxyn, which is used for treating ADHD and the short-term treatment of obesity.

Determining exactly how long methamphetamine is detectable in the body depends on many variables, including the type of test used, the method of use, and a person's unique physical characteristics. Methamphetamine can be detected for a shorter period of time with some tests but can be visible for up to three months in others.

How Long Does It Take to Feel Effects?

The effects of methamphetamine begin rapidly after intravenous use or when it is smoked. The primary effects last from four to eight hours, with residual effects lasting up to 12 hours. Amphetamine (a methamphetamine metabolite) is detectable in drug tests long after the person feels back to normal.

The effects of methamphetamine vary widely between prescribed therapeutic doses compared to dosages usually used by people who misuse meth. Prescription doses of 10mg to 30mg can improve reaction time, relieve fatigue, improve cognitive function testing, increase subjective feelings of alertness, increase time estimation, and increase euphoria.

However, a larger dose of meth can cause the following effects:

• Agitation
• Depressed reflexes
• Inability to focus attention on divided attention tasks
• Inability to follow directions
• Inattention
• Increased reaction time
• Motor excitation
• Poor balance and coordination
• Restlessness
• Time distortion

Driving Concerns

According to the National Highway Traffic Safety Administration (NHTSA), drivers who are under the influence of methamphetamine display a wide variety of behaviors including:

• Accidents
• Agitation
• Awkward movements
• Disorientation
• Erratic driving
• Irrational or violent behavior, and unconsciousness
• Lane travel
• Nervousness
• Rapid and non-stop speech
• Speeding
• Staggering
• Unintelligible speech

In the 101 cases reviewed by NHTSA in which meth was the only drug detected, impairment was attributed to "distraction, disorientation, motor excitation, hyperactive reflexes, general cognitive impairment, or withdrawal, fatigue, and hypersomnolence."

Meth and Alcohol

Some believe that methamphetamine can reverse some of the impairment effects of alcohol. That's because meth may restore alcohol-induced impairment in simple repetitive tasks of short duration. However, NHTSA research has uncovered no restoration of alcohol-induced deficits of balance and steadiness.

The combination can also increase the risk of alcohol poisoning since people do not realize how much they’ve had to drink.

How Long Does Methamphetamine Last?

The half-life of methamphetamine is an average of 10 hours. This means it takes about 10 hours for half of the ingested dose to be metabolized and eliminated from the bloodstream. 

When taken orally, concentrations of methamphetamine peak in the bloodstream between 2.6 and 3.6 hours, and the amphetamine metabolite peaks at 12 hours. If meth is taken intravenously, the elimination half-life is a little longer at about 12.2 hours.

Methamphetamine is metabolized by a liver enzyme and is excreted by the kidneys in urine. It is metabolized (or broken down) into amphetamine, and 4-hydromethamphetamine.

Various testing methods have different estimated ranges of times or detection windows, during which meth can be picked up after a person has taken the drug.

Urine

Meth is typically detectable in urine for one to four days but may be detectable for up to a week after heavy, chronic use. A urine test typically shows a higher concentration of meth than other drug tests because the drug's metabolites are eliminated through urine.

Blood

Blood tests can detect meth most quickly after it's been used, typically one to three days after last use.

Saliva

Meth can be detected in saliva for one to four days after the last use.

Hair

A hair follicle test can detect meth in your system for up to 90 days.

False Positive Testing

While a useful, simple, and inexpensive tool, immunoassays (one of the most common types of urine drug screen) can give false-positive results. There are certain medications that may produce a false positive result.

• Antidepressants such as bupropion, fluoxetine, trazodone, and selegiline
• Ephedra or ephedra-containing products
• Metformin used to treat type 2 diabetes (sold as Fortamet, Glucophage, Glumteza, Glucophage XR, and Riomet)
• OTC medications including antihistamines, nasal inhalers, and cold medicines that contain pseudoephedrine and/or promethazine
• Ritalin (methylphenidate) used to treat ADHD
• Trandate (labetalol) an alpha- and beta-blocker used to control blood pressure

Testing to identify specific drugs, rather than classes of drugs, is needed to confirm a positive urine drug screen for methamphetamine. To ensure clinicians can accurately interpret your drug screen results, always disclose any prescription or over-the-counter medications you are taking.

Factors That Affect Detection Time

The timetable for detecting methamphetamine in the human body depends on the individual's health, metabolism, age, physical activity, and frequency of use, making it difficult to determine how long meth will show up on a drug test.

• Overall health: Your overall health, including liver and kidney function, can play a role in how quickly meth is processed and cleared from your body.
• Frequency of use: People who use amphetamine very frequently will have longer detection times than those who use the drug one time.
• Metabolic rate: People with a high metabolism tend to process and excrete amphetamine more quickly than those with a slower metabolism. Age, activity level, and overall health can all play a role in your metabolic rate.
• Smoking vs. injecting: Whether you take the drug orally or intravenously can impact detection time. If you take it orally, it will be eliminated slightly more rapidly than if you inject the drug. If, on the other hand, you've been prescribed Adderall and take it as prescribed, the drug will likely remain in your bloodstream for longer periods of time.

How to Get Methamphetamine Out of Your System

There are plenty of false claims and myths when it comes to how to pass a drug test.

For example, there are false that "baking soda bombs," which is a mixture of water, bleach, and baking soda, mask the presence of methamphetamine in urine. There is no proven research that this works, and further, you take an enormous health risk when you ingest any amount of bleach.

The only way to get meth out of your system is to stop using the drug and allowing your body time to metabolize and eliminate it. Staying healthy by getting regular exercise and drinking plenty of water may also help you metabolize the substance more quickly.

Symptoms of Overdose

One of the main reasons to be aware of how long meth remains in the system is the risk of overdose. Here are some symptoms of a meth overdose:

• Chest pain
• Difficulty breathing
• Extremely high body temperature
• Heart attack
• Irregular heartbeat
• Kidney damage or failure
• Paranoia
• Seizures
• Severe agitation
• Stroke

Getting Help

If you're concerned about having too much meth in your system or testing positive for the drug, it's likely time to seek help or consult your doctor. If you use meth heavily and/or regularly, it's best to detox from the drug under the guidance of a medical professional who can guide you safely through the withdrawal and treatment process.

Twenty four hours after you stop using meth, you can expect to experience symptoms of withdrawal, which can range from mild to severe, depending on the frequency of use and dependency. Some common signs and symptoms of meth withdrawal include:

• Anxiety
• Cravings
• Depression
• Fatigue and sleepiness
• Increased appetite

If you or someone you love wants to quit using meth, there are steps you can take to get through the withdrawal process and succeed in your recovery.