DXM Drug Test: How Long Does DXM Stay In System?

Last Updated: December 18, 2019

How long does DXM stay in the system? DXM class of medication is absorbed quickly and has an elimination half-life of 2-4 hours. The half-life of dextromethorphan varies. In extensive metabolizers, half-life time may be shorter than 2 hours. On the other hand, poor metabolizers may need up to 24 hours to eliminate dextromethorphan from the system completely.
Half-life and dextromethorphan drug test are closely related subjects, as this chemical is easier to detect in poor metabolizers. This medication is excreted from the body via the renal pathway. Cases of severe intoxication and/or chronic use will result in longer elimination time.

DXM Half-Life Time

What is the half-life of dextromethorphan? DXM elimination half-life is most often used synonymously with the term biological half-life, which is the total amount of time an organism needs to remove a chemical. DXM half-life is sometimes measured by plasma half-life. Plasma method measures the amount of time it takes for plasma concentrations of a compound to halve.
The exact length of half-life time depends not only on the speed of metabolism. DXM HBR has a shorter half-life, due to fast absorption time. DXM Polistirex, on the other hand, has a longer half-life. This is due to the longer release time of Polistirex, meaning that this form of medication is easier to detect by a drug test.
Purified forms of the chemical have a shorter elimination time than the combination of dextromethorphan and quinidine, for example. When mixed with quinidine, dextromethorphan will be detectable via drug test for longer than 13 hours, even in fast metabolizers. DXM only products will thus have a shorter biological half-life.

Dextromethorphan Metabolism

This cough syrup medication is metabolized by the liver, which breaks down this chemical by making dextromethorphan metabolites. Enzyme metabolism of DXM relies heavily on cytochrome P450 enzyme, which is dysfunctional in poor metabolizers. These people cannot break down the chemical, which stays in their bodies for more extended periods. Other enzymes are also involved, but their contribution is less clear.

One study has purported to assess 24-hour dextromethorphan metabolism in the US population by taking two samples of blood plasma. Previously, 252 participants were given 30 mg of dextromethorphan. It has been found that 84% of subjects were fast metabolizers, while 9% of participants were slow metabolizers.

The main dextromethorphan metabolism pathway goes through the hepatic portal vein, which carries blood from the gastrointestinal tract to the liver.

Dextromethorphan On A Drug Test

Does dextromethorphan show up on a drug test? It is not easy to answer this question. This substance isn’t a part of standard drug tests. Even extended drug tests don’t include it as their essential part. And there is a simple reason for this – dextromethorphan is legal. However, with more cases of adolescent DXM addiction, more and more companies have started to include dextromethorphan as a standard part of their drug tests.

dxm on the drug test

How many days does it take for DXM to get out of the system? There are no straightforward answers, as there are a lot of different drug tests available. Most dextromethorphan will be eliminated in a matter of days, while traces of dextromethorphan will stay in hair follicles months after use.

How Long Does Dextromethorphan Stay In The Urine?

As this cough syrup drug isn’t a standard part of most drug tests, there are no definite answers to this question. A temporary period of 5 days is often accepted as the upper limit. Dextromethorphan urine tests are still rarely used.

How Long Does Dextromethorphan Stay In The Blood?

In short metabolizers, traces of this substance can be found in blood plasma 4 hours after ingestion. After the first few hours, all traces of the chemical are eliminated from the blood, which is why this method of drug tests isn’t the most popular one. This also means that the dextromethorphan military drug test isn’t something to be afraid of.

Hair Testing For DXM: May It Be Revealed In Follicles?

Hair follicle drug tests are the most extensive drug tests available, and these tests will be able to detect this chemical month after consumption (the exact length is unknown).

Is It Possible To Detect DXM On Saliva Test?

A group of researchers from the US developed an efficient method for detecting DXM in saliva. This is still a novel technique, and it is unclear whether it can detect the medication days after ingestion.

Factors That Influence On Time Of Staying Dextromethorphan In The System

Higher doses will stay in the body for more extended periods. Severe acute intoxication is easier to detect by drug tests than moderate use. For instance, ingesting 600 mg DXM dose counts as severe intoxication. Similarly, acute cases involve combinations with other substances, such as Zoloft and dextromethorphan.

  • In chronic users, the drug may stay in the system longer, mainly if detox programs for DXM aren’t undertaken.
  • Fast and poor DXM metabolizers have different genes that control the P450 enzyme expression. Slow metabolizers sometimes have completely inactive genes that control metabolism.
  • As the body ages, metabolism gets slower, which means that dextromethorphan elimination also slows down.
  • DXM pharmacokinetics have complex interactions with body mass. Generally speaking, skinnier people feel the effects more quickly and have shorter DXM half-life than people with more bodyweight. However, people with a significant muscle mass may also process the drug quite fast, even if the body mass is above-average.

This time also does not depend on taking the medication in other forms, such as dextromethorphan capsules, or when combined with other substances.

Will Dextromethorphan Make One Fail A Drug Test?

Is it possible to fail a drug test with dextromethorphan? This medication can be detected via different drug tests, even though most drug tests focus on illicit substances.

DXM false positive drug test is one of the most debated issues with respect to DXM drug tests. More specifically, ingestion of this drug might be falsely identified as PCP consumption, which is a big problem considering that PCP is illegal.

Ways Of Getting DXM Out Of System

  • Activated charcoal is one of the ways to get DXM out of the body. Commonly, activated charcoal is mixed with water, and ingested after the onset of DXM overdose symptoms, because authorities only allow charcoal utilization for overdose treatment.
  • Calcium D-Glucarate, which detoxifies the liver,  is another way to get DXM out of the system. Proceed with caution, as this chemical’s detox properties are scarcely tested, and it’s mostly used for cancer treatment.
  • Exercise is an effective natural way to speed up organic processes in the body, and clean DXM out of the system. Drinking a lot of water, and sweating will also speed up the excretion of other substances, not only of dextromethorphan.
  • CYP2D6 (cytochrome P450) induction is a novel, but efficient way of eliminating this substance from the body. A recent study proved that Exogenous and Endogenous Corticosteroids could induce CYP2D6, and thus speed up the metabolism of this medication.

What To Do After Dextromethorphan Leaves The Body?

Even when the drug leaves the body, there may remain some psychological and physiological symptoms (e.g., DXM headache). Severe symptoms often warrant psychotherapeutic treatment and counseling. A primary part of the addiction therapy is the replacement of this cough remedy with DXM analogs.

pharmacist choosing cough syrup

Chronic users and addicts will have a longer half-life of this cough syrup medication, and these people will need to be treated in drug rehabilitation institutions. Purified forms of this medication, like DXM crystals, are very potent and increase the chances of overdose.

Is DXM addictive? Although less prominent than addiction syndromes some other substances produce, people can get addicted to the popular cough syrup medication. Chronic consumption results in a longer half-life and more chances of dextromethorphan showing up on a drug test. The onset of addiction is often insidious, especially in people who try to justify their bad habits (using DXM for sleep is a frequent justification).

Page Sources

  1. Woodworth JR, Dennis SR, Moore L, Rotenberg KS. The polymorphic metabolism of dextromethorphan. 1987. https://www.ncbi.nlm.nih.gov/pubmed/3680565
  2. Storrow AB, Magoon MR, Norton J. The dextromethorphan defense: dextromethorphan and the opioid screen. 1995. https://www.ncbi.nlm.nih.gov/pubmed/7584765
  3. Muhammad Farooq, Edward J. Kelly, Jashvant D. Unadkat. CYP2D6 Is Inducible by Endogenous and Exogenous Corticosteroids. 2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4851303/
  4. Jochen Mutschler, Anne Koopmann, Martin Grosshans, Derik Hermann, Karl Mann, Falk Kiefer. Dextromethorphan Withdrawal and Dependence Syndrome. 2010. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2925345/

Published on: August 6th, 2019

Updated on: December 18th, 2019

About Author

Peter J. Grinspoon, MD

Dr. Peter Grinspoon is an experienced physician with long-term clinical practice experience. As a former analgesic addict, Dr. Grinspoon knows precisely how important it is to provide patients with effective treatment and support. Medical writing for him is the way to communicate with people and inform them about their health.


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