Dextromethorpan (DXM)

Overview

Dextromethorphan (DXM) is a widely used antitussive (cough suppressant) found in over 120 over-the-counter (OTC) cold and cough medications. It is also known by synonyms such as D-Methorphan and appears in numerous preparations either as a primary ingredient or combined with antihistamines, analgesics, decongestants, or expectorants. While legally accessible in most countries, restrictions exist in regions such as the UAE, France, Sweden, Estonia, and Latvia.

Dextromethorphan is misused recreationally due to its ability to cause euphoria and auditory/visual hallucinations when taken in high doses. Street names include DM, Robo, Rojo, Velvet, and slang terms include Robo-tripping, Skittling, Dexing, or Triple C (referring to Coricidin Cough & Cold).

Pharmacologically, DXM affects serotonin, norepinephrine, NMDA, and sigma-1 receptors, interacting with pathways involved in depression and neural modulation. DXM testing is used for forensic investigations, monitoring drug abuse, clinical evaluation of intoxication, and routine health screening in individuals known or suspected to misuse OTC cough products.

Testing samples include urine, blood, hair, and saliva, with laboratory evaluation done through chromatography, spectroscopy, and immunoassay methods.

Symptoms

Symptoms associated with DXM misuse or overdose result from CNS stimulation, serotonin imbalance, and impaired coordination. The PDF categorizes these symptoms across multiple body systems:

Cardiovascular Symptoms:

1. Tachycardia
2. Hypertension

Neurological Symptoms:

1. Seizures
2. Convulsions
3. Slurred speech
4. Loss of balance
5. Difficulty in coordination

Gastrointestinal Symptoms:

1. Nausea and vomiting

Respiratory Symptoms:

1. Shallow or difficult breathing

Mental Status Symptoms:

1. Hallucinations
2. Confusion
3. Disorientation

Severe Effects:

1. Unconsciousness
2. Coma
3. Death

These symptoms typically drive clinical evaluation and confirmatory testing when DXM intoxication or overdose is suspected.

Causes

The PDF highlights several causes that lead to detectable DXM levels or intoxication:

1. Recreational Misuse:

High-dose misuse of OTC cough syrups or tablets to achieve hallucinations, euphoria, or dissociative effects.

2. Polydrug Use or Contaminated Formulations:

DXM products may be mixed with antihistamines, analgesics, or decongestants, enhancing toxicity.

3. Overdose During Therapeutic Use:

Accidental overdose due to consuming multiple DXM-containing products simultaneously.

4. Neurochemical Effects:

DXM interacts with NMDA, serotonin, norepinephrine, and sigma-1 receptors, causing neurotoxicity when excessively stimulated.

5. Testing-Related Causes of Erroneous Detection:

1. Technical or procedural errors
2. Interfering substances in urine
3. Sample adulteration (bleach, alum)
4. Variability in metabolic excretion
5. Dilution or substitution causing false-negative results

The document clearly states that GC/MS is the preferred confirmatory method due to its high accuracy.

Risk Factors

Risk factors outlined in the PDF include behavioral, physiological, and testing-related factors:

Risk Factors for DXM Abuse:

1. Adolescents and young adults, who commonly misuse OTC cough medicines
2. Individuals with access to OTC multi-ingredient cold preparations
3. Recreational drug users engaging in “robo-tripping” or “skittling”
4. Persons seeking dissociation or hallucination through legal OTC products

Risk Factors for Severe Toxicity:

1. Consuming DXM alongside other drugs, alcohol, or psychoactive medications
2. Using products with multiple active ingredients
3. Large doses taken rapidly
4. Preexisting neurological or cardiovascular conditions

Risk Factors Affecting Testing Accuracy:

1. Sample adulteration
2. Improper collection/transport
3. Variability in individual metabolism
4. Fluid intake altering urine concentrations
5. Drug levels below the detection cut-off

The PDF provides cut-off values for labeling a test positive:

1. Urine: > 50–100 ng/mL
2. Plasma: > 10–50 ng/mL
3. Hair: > 0.1–1 ng/mg
4. Saliva: > 10–50 ng/mL

Prevention

The PDF emphasizes prevention mainly through proper testing procedures, sample integrity, and monitoring to reduce DXM misuse.

Testing-Related Prevention:

1. Collect urine in a clean, sterile container, ensuring no contamination or tampering.
2. For blood testing, collect 3.0 mL in EDTA (lavender-capped) tube.
3. For hair testing, collect close to the scalp and place in clean foil.
4. Saliva samples should be collected by swabbing for rapid detection.
5. Use reliable methods such as LC-MS/MS, GC-MS, HPLC-MS, CE-MS, and immunoassays.
6. Always confirm positive screening results using GC/MS.
7. Avoid adulterants or dilution to prevent false results.

Clinical & Behavioral Prevention:

1. Monitor high-risk individuals (especially adolescents) for misuse of DXM-containing products.
2. Use follow-up testing for individuals with previous DXM toxicity.
3. Educate about dangers of high-dose DXM misuse, including hallucinations, respiratory depression, coma, and death.