DXM: general

DXM (dextromethorphan) is a synthetic drug related to morphine, used in over-the-counter cough and cold remedies — it's the ingredient in more than 140 such products and has been the most-used OTC cough suppressant since it was introduced in 1958 [1][2][3][4]. It's chemically related to codeine but is not an opiate [2], and it was introduced as the first non-opioid cough suppressant [3]. It doesn't have significant affinity for the mu-opioid receptor activity typical of morphinan compounds [4].

Recreational users intentionally exceed recommended doses to experience heightened awareness, altered time perception, and visual hallucinations [5]. At supratherapeutic doses, DXM mimics the activity of dissociative hallucinogens such as PCP or ketamine [3]. Recreational use of DXM accounts for approximately 6,000 emergency department visits a year in the US [5][6], and misuse is concentrated among younger people — about one million people aged 12–25 in the US misuse DXM-containing products annually [6].

As with dissociatives generally, there's no specific antidote for toxicity [7]. Most people who misuse DXM are reported to take it orally, though some are reported to snort the pure powdered form [2]. As with dissociatives generally, overdose can range from unpleasant to life-threatening depending on dose, route, and whether other substances are involved [8]; reported signs include severe eye movement abnormalities, unresponsiveness, vomiting with aspiration risk while unconscious, dangerously slowed breathing, seizures, and extremely elevated heart rate or blood pressure [8]. If any of that shows up, it's an emergency regardless of what else was taken.

References

1. Dextromethorphan | Cough Suppressant, Antitussive, DM — Encyclopædia Britannica
2. DXM (Dextromethorphan) — National Drug Intelligence Center (NDIC), U.S. Department of Justice
3. Classics in Chemical Neuroscience: Dextromethorphan (DXM) — PubMed
4. Dextromethorphan — Wikipedia
5. Dextromethorphan abuse — Poison Control (National Capital Poison Center)
6. Dextromethorphan misuse and poisoning: Clinical features and diagnosis — UpToDate
7. Dextromethorphan abuse — Canadian Medical Association Journal (CMAJ)
8. Dissociatives: Dosage, Effects, Duration & Safety Guide — SubstanceWiki