Dextromethorphan’s Hidden Psyche: How a Cough Suppressant Might Be More Than Just a Cold Remedy

At doses far above what’s typically used for cough suppression, dextromethorphan (DXM) — the active ingredient in many over-the-counter cough medicines — may produce psychedelic effects. A new systematic review of eight studies suggests this is possible, but the science is still in its infancy.

Bottom line: This review shows that DXM can induce hallucinatory and mystical experiences at doses over 100 mg, but the evidence is limited and inconsistent.

The Psychedelic Potential of a Cough Medicine

Dextromethorphan is a cough suppressant found in many over-the-counter cold medications. At typical therapeutic doses (up to 120 mg), it works as a central nervous system depressant. But when taken in much higher amounts — often in combination with other substances like alcohol or caffeine — DXM becomes a recreational drug known for its dissociative and hallucinogenic effects.

These experiences, sometimes described as “empathy,” “mystical,” or “ego dissolution,” have led some to compare DXM to classic psychedelics like LSD or psilocybin.

The new systematic review, published in Europe PMC in June 2026, looked at eight studies involving a total of 104 participants, all of whom were given DXM in doses ranging from 100 to 960 mg. The studies included a mix of crossover trials, single-dose experiments, and ascending dose sequences.

The results were striking: psychedelic effects were observed at 100 mg, but the intensity of these experiences — including hallucinations, mystical phenomena, and altered cognition — increased significantly at 300 and 400 mg.

What’s more, adverse effects like nausea, vomiting, motor impairment, and cognitive slowing became more common as the dose increased beyond 200 mg. These findings suggest that while DXM can produce psychedelic-like states, the experience is far from benign. The researchers caution that the evidence is still very limited, and the studies they reviewed were all at high or some risk of bias, with low certainty for most outcomes.

But what if this common cough syrup is doing something more than just suppressing coughs?

A Dose-Response That Defies Expectations

The review’s authors were struck by the dose-response pattern they observed. At 100 mg, participants reported mild psychedelic effects — sensations of time distortion, emotional intensity, and a sense of being “outside the body.” But as the dose increased, these effects became more pronounced. At 300 mg, the reports of hallucinations, mystical experiences, and ego dissolution spiked. The same pattern was seen at 400 mg, with even stronger reports of altered perception and emotional release.

What’s fascinating is that this dose-response curve is not linear. The researchers found that the intensity of the psychedelic effects didn’t simply increase with dose — it seemed to follow a more complex pattern, with a sharp rise in experience intensity between 200 mg and 300 mg, followed by a plateau or even a slight decline at higher doses. This suggests that the brain may be hitting a threshold at around 300 mg, where the psychedelic effects become more intense, but the body starts to react with more negative side effects.

This is a crucial point. While the psychedelic effects are strongest at 300 and 400 mg, the risk of adverse effects also rises.

The Science Behind the Psychedelic Experience

So, what’s actually happening in the brain when someone takes DXM in high doses? DXM is a dissociative drug that works by binding to sigma-1 (σ1) receptors in the brain. These receptors are involved in a range of functions, including mood regulation, memory, and perception. When DXM binds to these receptors, it can produce a sense of detachment from the self, altered sensory perception, and a heightened emotional state — all hallmarks of a psychedelic experience.

But the exact mechanism by which DXM produces these effects is still not fully understood. Some researchers believe that DXM may also interact with other receptors, such as NMDA and opioid receptors, to enhance its psychoactive properties. However, the review found that most of the studies they analyzed did not provide a clear explanation of the underlying neurobiological mechanisms. This is a gap in the research that needs to be addressed before DXM can be considered a viable therapeutic agent.

What’s more, the review highlights that the majority of the studies they analyzed were observational or case series, rather than randomized controlled trials. This means that the results are not as reliable as they could be. The researchers emphasize that the evidence for DXM’s psychedelic effects is still preliminary and that more rigorous, large-scale studies are needed to determine its safety and efficacy.

Frequently Asked Questions

Q: Is DXM safe to use for its psychedelic effects?
A: The review found that while DXM can produce psychedelic effects at doses over 100 mg, the risk of adverse effects — such as nausea, vomiting, and cognitive slowing — increases with higher doses. The evidence is still limited, and the studies included in the review were all at high or some risk of bias. Therefore, the safety of using DXM for its psychedelic effects is not well established.

Q: Can DXM be used as a treatment for psychiatric disorders?
A: The review suggests that DXM may have potential as a treatment for certain psychiatric conditions, but the evidence is still very limited. More research is needed to determine its safety and efficacy in a clinical setting.

Q: How does DXM compare to other psychedelics like LSD or psilocybin?
A: The review notes that DXM produces effects similar to classic psychedelics, but the exact mechanism is not fully understood. Unlike LSD or psilocybin, which primarily act on serotonin receptors, DXM interacts with sigma-1 receptors. This may explain some of the differences in the psychedelic experience.

Q: What are the long-term effects of DXM use?
A: The review does not provide any information about the long-term effects of DXM use. More research is needed to determine how repeated exposure to DXM affects the brain and body.

Q: Is DXM legal to use for its psychedelic effects?
A: DXM is legal in the United States when used as a cough suppressant in over-the-counter medications. However, its use for recreational or psychedelic purposes is not regulated and may be considered illegal in some jurisdictions. Always check local laws before using DXM for any purpose other than its intended use.

Sources

• ¶Dextromethorphan Beyond the Cough: Exploring Its Psychedelic Potential: A Systematic Review
• ¶Repeated dextromethorphan administration in adolescent rats produces long-lasting behavioral alterations
• ¶Future Therapeutic Strategies for Alzheimer’s Disease: Focus on Behavioral and Psychological Symptoms

Educational Disclaimer

This article is for informational and educational purposes only. It is not medical advice, mental health advice, diagnosis, treatment guidance, or a recommendation to use any substance, supplement, therapy, or protocol.

We review publicly available research and explain what the evidence may suggest. Some studies may be early-stage, observational, animal-based, lab-based, theoretical, or incomplete. Always consult a qualified professional before making health-related decisions.

If you or someone you know is struggling, you are not alone. In the US, call or text 988 (Suicide & Crisis Lifeline). Elsewhere, contact your local emergency or crisis service.

Researched and drafted by Spore, ShroomWire’s AI research assistant, and reviewed by the ShroomWire editorial team before publishing.