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Summary sheet: Dextromethorphan
Chemical Nomenclature
Common names DXM, DMO, DM, Dex, Robitussin, Delsym, DexAlone, Duract
Substitutive name Dextromethorphan
Systematic name (4bS,8aR,9S)-3-Methoxy-11-methyl-6,7,8,8a,9,10-hexahydro-5H-9,4b-(epiminoethano)phenanthrene
Class Membership
Psychoactive class Dissociative
Chemical class Morphinan
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Threshold 75 mg
Light 100 - 200 mg
Common 200 - 400 mg
Strong 400 - 700 mg
Heavy 700 mg +
Total 8 - 12 hours
Onset 30 - 120 minutes
Come up 60 - 120 minutes
Peak 3 - 6 hours
Offset 2 - 4 hours
After effects 4 - 24 hours

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.


Dextromethorphan (also known as robo, dex, DM, and DXM) is a dissociative substance of the morphinan class. It is the primary active ingredient in many common over-the-counter (OTC) cold and cough medicines. When exceeding approved doses, DXM produces dissociative effects similar to those of ketamine and phencyclidine (PCP). It acts as a noncompetitive NMDA receptor antagonist [1].

DXM was first reported in 1953 and approved for use as a cough suppressant in the United States in 1958.[2] After its approval, it was introduced as an OTC medication under the name Romilar. As early as 1975, the popularity and extensive abuse of DXM was recognized, and Romilar was voluntarily removed from the OTC market.[3] A few years later, companies began introducing various refined DXM products designed to deter abuse, such as including ingredients with an unpleasant taste.

However, recreational use of DXM has persisted and is a considered a growing trend, particularly among teenagers seeking low cost and easily available highs.[4]

Subjective effects include dissociation, time distortion, bodily hallucinations, immersion enhancement, motor control loss, euphoria, and ego loss. Users commonly describe low doses as producing an alcohol-like intoxication while higher doses produce effects similar to ketamine or PCP. It is often reported to produce a strong, uncomfortable body load with significant nausea.

The effects and tolerability of DXM are highly variable between users which may be due to individual differences in the genes underlying metabolism. As a result, many users find the experience of DXM to be either unpleasant, neutral, or dull, while others report mystical-like psychedelic experiences.

It should be noted that DXM in freebase form (as found in Robocough RoboTablets) is around 27-37% more potent than its hydrobromide form due to a higher concentration of DXM by weight. One should take this into account when calculating their dose to avoid a potential overdose.

The toxicity of DXM in recreational doses is unclear and has been the subject of controversy. There is some evidence that suggests NMDA antagonists may have neurotoxic effects when used in excess. Many cases of DXM dependence and abuse have been documented.[citation needed] It is strongly advised to use harm reduction practices if using this substance.

History and culture

1968 advertisement of Romilar DXM tablets

The racemic parent compound of dextromethorphan, racemethorphan, was first described in a Swiss and US patent application from Hoffmann-La Roche in 1946 and 1947, respectively. A patent was granted in 1950. A resolution of the two isomers of racemethorphan with tartaric acid was published in 1952,[5] and DXM was successfully tested in 1954 as part of US Navy and CIA-funded research on nonaddictive substitutes for codeine.[6]

DXM was approved by the FDA in 1958 as an over-the-counter antitussive, or cough suppressant.[5] As had been initially hoped, DXM was a solution for some of the problems associated with the use of codeine phosphate as a cough suppressant, such as sedation and opiate dependence, but like the dissociative anesthetics phencyclidine and ketamine, DXM later became associated with nonmedical use.[3][5]

During the 1960s and 1970s, dextromethorphan became available in an over-the-counter tablet form by the brand name Romilar. In 1973, Romilar was taken off the shelves after a burst in sales because of frequent misuse, and was replaced by cough syrup in an attempt to cut down on abuse.[3]

The advent of widespread internet access in the 1990s allowed users to rapidly disseminate information about DXM, and online discussion groups formed around use and acquisition of the substance.

As early as 1996, DXM HBr powder could be purchased in bulk from online retailers, allowing users to avoid consuming DXM in syrup preparations.[5] As of January 1, 2012, dextromethorphan is prohibited for sale to minors in the state of California, except with a doctor's prescription.[7]


Generic structure of morphinan molecule.

Dextromethorphan is a dextrorotatory molecule of the morphinan class. It contains a phenanthrene core structure with one aromatic ring (benzene) bound to two saturated rings (cyclohexane). Additionally, it contains a saturated piperidine ring attached to R9 and R13 of the core structure. DXM is substituted at RN with a methyl group and at R3 with a methoxy group.


Further information: NMDA receptor antagonist

The pharmacology of DXM is not completely understood. In vitro studies suggest that the primary mechanism of action of DXM is blockade of N-methyl-D-aspartate (NMDA) receptors. NMDA receptors are a type of glutamate receptor; glutamate is the primary excitatory neurotransmitter. Blockade of NMDA receptors therefore interferes with excitatory signaling in the central nervous system. This mechanism of action is similar to ketamine and PCP.

Rather than acting as a direct NMDA receptor antagonist itself, dextromethorphan acts as a prodrug of its much more potent metabolite dextrorphan, and this is the actual mediator of its dissociative effects.

Additional pharmacological mechanisms include actions as a nonselective serotonin reuptake inhibitor[8], alpha-3 beta-4 nicotinic receptor antagonist[9] and a sigma-1 receptor agonist.[10][11]

At high doses, DXM can cause an increase in systolic and diastolic blood pressure along with an increase in heart rate.[12] DXM also increases blood plasma levels of adrenocorticotropic hormone (ACTH) and corticosterone.[13]

Although DXM is a morphine derivative, it isn't a strong μ-opioid agonist unlike most compounds in that class, such as heroin and codeine.

Binding Sites Binding Affinity Ki (nM)[14]
NMDA 8945
Sigma-1 138
NET 240
μ-opioid 1280
κ-opioid 7000
δ-opioid 11500


Metabolism of Dextromethorphan

DXM is O-demethylated into Dextrorphan (DXO / D-3-hydroxy-N-methylmorphinan) by the CYP2D6 enzyme.[15][16] DXM is also N-demethylated into 3-methoxymorphinan (MEM / Morphinan) by the CYP3A4 enzyme[16][17] and to a lesser extent CYP3A5.[18]

Dextrorphan and 3-methoxymorphinan are both metabolized into 3-hydroxymorphinan. Dextrorphan is N-demethylated by CYP3A4 and 3-Methoxymorphinan is O-demethylated by CYP2D6. CYP2D6 O-demethylation is more effective than CYP3A4 N-demethylation.[16]

Variations of how individual persons metabolize DXM may significantly alter the nature of the experience. Poor metabolizers clear less DXM than the average person, leading to a higher ratio of DXM to DXO in the bloodstream[19], as well as overall increased potency and duration, due to less lost to the largely inactive metabolites 3MM and 3HM. CYP2D6 and CYP3A4 inhibitors have a similar effect.


Dextrorphan is produced by O-demethylation of dextromethorphan through the CYP2D6 enzyme and contributes to the psychoactive effects of dextromethorphan.[20] It is pharmacologically similar to that of dextromethorphan (DXM); however, it is much more potent as an NMDA receptor antagonist[14] as well as much less active as a selective serotonin reuptake inhibitor.[13]

It is also about 3-fold less potent of a α3β4 nicotinic receptor antagonist than DXM[9] and has a lower affinity for sigma-1 receptors.[10]

Binding Sites Binding Affinity Ki (nM)[14]
NMDA 486
Sigma-1 351
SERT 484
NET 340
μ-opioid 420
κ-opioid 5950
δ-opioid 34700


3-Methoxymorphinan (also known as 3MM) is produced by the N-demethylation of dextromethorphan by the CYP3A4 enzyme[16] and inhibits the CYP2D6 enzyme.[21] It has local anaesthetic effects.[22]


3-Hydroxymorphinan (also known as 3HM) is produced by O-demethylation of 3-methoxymorphinan by CYP2D6 and metabolization of dextrorphan by CYP3A4 and CYP3A5[23]. 3-Hydroxymorphinan exhibits neuroprotective and neurotrophic effects.[24][25][26]

Subjective effects

The head space of DXM is often described as distinctly hallucinogenic, impairing, disorientating and generally less clear-headed in comparison to that of MXE and ketamine.

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Physical effects

Visual effects

Cognitive effects

Disconnective effects

Multi-sensory effects



The online DXM community categorizes the types of experiences that can result from oral DXM use into five "plateaus" which are characterized by qualitatively distinct effects.

First Plateau (1.5 - 2.5 mg/kg) - The effects felt in the first plateau are usually not very intense. They can include but are not limited to: cognitive euphoria, increased music appreciation, time distortion, pupil dilation, and stimulation. First plateau is often described as a "drunk" feeling.

Second Plateau (2.5 - 7.5 mg/kg) - Many DXM users consider this the to be the most recreational plateau. The second plateau is more sedating than stimulating, while euphoria and visual disconnection are more intense. Additional effects of the second plateau can include but are not limited to: wakefulness, physical euphoria, spatial disorientation, perception of bodily lightness, frame rate suppression, and increased music appreciation. Many users of DXM do not proceed past the second plateau, as the desired effects are thought to be outweighed by the increasing adverse effects, including a more pronounced "body load". Music is often reported to be greatly enhanced at this plateau, described as rich, clear, and amplified.

Third Plateau (7.5 - 15 mg/kg) - The Third Plateau is reported to be much more intense than the second, and should be gradually worked up towards. The effects of the third plateau can include but are not limited to: dissociation, sedation, nausea (during comeup), memory suppression and ego death, auditory hallucinations, internal hallucinations, cognitive dysphoria, euphoria, anxiety, delusions, and all the effects of the second plateau. Third plateau trips have been described as euphoric and profound by some users.

Some users have described an omnipotent feeling that one is in control of the entire universe, accompanied with CEVs. Closed eye visuals are often present, consisting of usually darker colored geometric patterns, vast landscapes, and scenes. Music can greatly enhance the effect, although it can also sound tinny and distorted. Users have reported being able to break down every single fragment of a song and visualize all of it in their minds; reliving past memories has also been reported.

The third plateau is often reported to be extremely introspective and a number of users describe being inspired to improve their lives. The afterglow is reported as tiring, but a mood boost is often reported for days or weeks afterward.

Fourth Plateau (15 - 20 mg/kg) - The effects of the fourth plateau can include but are not limited to external hallucinations, complete dissociation, and all the effects of the third plateau, with greater intensity. Amnesia can occur, leading to memory blackouts or brownouts.

Doses of DXM in this range are very dangerous and have a high risk of injury and overdose, and are therefore advised against.

Fifth Plateau (also known as "Plateau Sigma") -

Plateau Sigma is neurotoxic and has high potential to cause serotonin syndrome, it is therefore strongly advised against.

A common method to reach "Plateau Sigma" is to take a second plateau dose, followed by another second plateau dose three hours later, then take a fourth plateau dose upon the peak of the second dose. Plateau sigma usually results in delirious hallucinations, dysphoria, delirium, psychosis, and anxiety; plateau sigma's subjective experience is therefore usually very unpleasant and unpredictable. Separate dosages are needed to achieve plateau sigma because the initial dosages pre-occupy the hepatic enzymes that convert DXM to Dextorphan, leading to a higher blood concentration of un-converted DXM (followed by its own subjective effects) and a longer process for it to clear from the body. Due to this enzymatic effect, plateau sigma can accidentally occur due to redosages, drug/medication interactions (i.e substrates for CYP2D6), and/or enzyme deficiency/liver dysfunction.[27] Due to the variance in how each individual clears DXM from the body, the subjective experience of plateau sigma can potentially last from one to four days.

Experience reports

Anecdotal reports which describe the effects of this compound within our experience index include:

Additional experience reports can be found here:

Common usage

Available forms

DXM is available in several forms that can be found over the counter or online.

  • Cough syrup is the most common form online and over the counter. Well-known brands include Benylin, DayQuil, Delsym, NyQuil, Robitussin, Omol, and Siltussin. Many of these products contain other medicines, including aspirin, acetaminophen, caffeine, guaifenesin or pseudoephedrine. Within the UK, Benylin dry coughs 7.5mg/5ml syrup (225mg dosage per 150ml bottle) is available behind the counter at every pharmacy. Generic brands are also available within these shops for a consistently lower price. In recent years in the United States, a DXM formulation called RoboCough (which has no other active ingredients, and comes in small bottles) has become popular.
  • Gel capsules, lozenges, soft pastilles, and pills are available online and over the counter. Well-known brands include Benylin, Comtrex, Coricidin, DayQuil, Mucinex, NyQuil, and Robitussin. Many of these products contain other medicines, including aspirin, acetaminophen, caffeine, guaifenesin or pseudoephedrine.
  • Pure powder is available online. This is the safest way to use DXM, as there is no danger of overdose from secondary chemicals. However, one should still test their powder to avoid ingesting toxic byproducts or a preparation falsely advertised as DXM powder.

It is important not to overdose on other active ingredients or a combination of them. Common ingredients also contained in cough syrup and pills include:

  • Acetaminophen: Also named Paracetamol or APAP, it is a non-steroidal anti-inflammatory drug. The recommended dose of acetaminophen in adults is 650 to 1,000 mg every 4 to 6 hours, not to exceed 4,000 mg in a 24-hour period. Single doses over 150 mg/kg or 7.5 g in adults have been considered potentially toxic, although the minimal dose associated with liver injury can range anywhere from 4 to 10 g. This dose will be substantially lower for younger adults.[28]
  • Guaifenesin: The maximum recommended daily dose for Guaifenesin is 2.4 grams. Guaifenesin overdose up to 4 grams or more have not been associated with overdose symptoms, besides causing nausea and vomiting.[29] This should not be taken as a lead and guaifenesin overdose should be avoided if possible.
  • Chlorphenamine: Known as an active ingredient in Coricidin, chlorphenamine acts as a blood pressure stabilizer. Chlorphenamine overdose has led to a number of circulatory complications and in combination with dextromethophan has resulted in many overdoses and death.[citation needed] Chlorphenamine should be avoided when taken in combination with DXM.
  • Phenylephrine: The maximum daily dose should be under 60 milligrams. Phenylephrine overdose has been associated with a range of dangerous cardiovascular problems, which may be amplified further by dextromethorphan.[citation needed] Phenylephrine should be avoided when taken in combination with DXM.
  • Pseudoephedrine: Overdose can cause cardiovascular problems.[citation needed] Pseudoephedrine should be avoided when taken in combination with DXM.
  • Caffeine: Caffeine overdose can result from as few as 400 to 600 milligrams. May increase cardiovascular side effects of DXM, but the extent to this is unknown.[citation needed] Caffeine should be avoided when taken in combination with DXM.
  • Diphenhydramine: Diphenhydramine in combination with dextromethorphan has a very low threshold for delirium and a complete detachment of reality. May also strain the circulatory system and heart in high doses.[citation needed]
  • Aspirin: Aspirin overdose starts below 300mg/kg and can become deadly at 500mg/kg.[citation needed] Higher doses of aspirin should be avoided in combination with DXM.
  • Dextromethorphan polistirex: This type of Dextromethorphan is used in the common brand Delsym for long cough and cold relive. The polistirex around the dextromethorphan causes the high of DXM to last much longer than intended, with some reports of the high lasting 18-24 hours instead of normal DXM lasting around 8-12 hours, which for some users could be very unpleasant. On top of that, you need more DXM polistirex to get the same high as regular DXM. This could lead to someone using too much DXM polistirex and overdosing to get the same effects as a moderate too high dose of normal DXM without the polistirex.
  • Doxylamine: This drug is found in NyQuil and is used as a sleep aid so the user has an easier time sleeping. Doxylamine's median lethal dose (LD 50) is estimated to be 50–500 mg/kg in humans and when ingested with DXM will have a very low threshold for delirium and complete detachment of reality due to the fact that it is a generation one antihistamine just like Diphenhydramine. Doxylamine in combination with DXM can also cause strong sedation and ataxia when combined with each other which would lead to impaired thinking and possibly unconsciousness.


Recommended introductory reading: DXM § Metabolism

Grapefruit juice is reported to be effective at potentiating the effects of DXM. For users who are drinking store bought syrup, this is useful as it means drinking less syrup. By inhibiting the enzyme CYP3A4, ingestion of grapefruit juice leads to DXM that would be metabolized into 3-MM, be metabolized into DXO instead. This leads to higher plasma concentrations of DXO, and slower degradation of DXO too, by inhibition of the conversion of DXO into 3-HM.

Near maximal potentiation remains for 4 hours after the drinking a cup (200–250 mL) of grapefruit juice, and drinking an amount beyond that doesn't increase effects significantly. On the other hand, frequent consumption of a cup at least three times a day, for a day or more, increases potentiation moreso than a lone (even if greater) quantity. After this, the potentiation also takes longer to wear off, suggesting frequent consumption of grapefruit juice has a cumulative effect.[30]

Preparation methods

Preparation methods for this compound within our tutorial index include:

Toxicity and harm potential


This toxicity and harm potential section is a stub.

As a result, it may contain incomplete or even dangerously wrong information! You can help by expanding upon or correcting it.
Note: Always conduct independent research and use harm reduction practices if using this substance.

The toxicity and long-term health effects of recreational DXM use in humans has not been studied in any scientific context and the exact toxic dosage is unknown.

Anecdotal evidence suggests that there do not seem to be any negative health effects attributed to simply trying DXM at low to moderate doses by itself and using it sparingly, however, many DXM users report that waiting a week between their respective plateaus before doing DXM again (one week after first plat., two weeks after 2nd plat., etc.) can potentially prevent or minimize severe damage to the kidneys and many other organs including the heart and liver due to an excess of assorted toxic chemicals in the blood stream after DXM use. This 1-4 week period gives your body time to filter out these chemicals and help get you back to baseline levels to where its safe to do again. Some more heavy users of DXM report that these chemicals can build up heavily over time if you do not follow these guidelines, which could mean waiting longer to do again after more heavy use between short periods. Independent research should always be done to ensure that a combination of two or more substances is safe before consumption.

Despite early speculation that DXM may cause neurotoxicity and Olney's lesions, it has not been shown to cause this effect in animals [31], However, many chronic users report significant issues with memory, attention, and mood that persist for many months after stopping usage. In rats,[32] oral administration of dextromethorphan did not cause neurotoxic effects in laboratory tests.[33] Oral administration of dextromethorphan repeatedly during adolescence, however, has been shown to impair learning in those rats during adulthood.[34]

It is strongly advised to use harm reduction practices if using this substance.

Dependence and abuse potential

As with other dissociatives, DXM produces dependence with chronic use and has moderate abuse potential. When dependence has developed, cravings and withdrawal effects may occur if a person suddenly stops their usage.

A formal survey of dextromethorphan users[35] showed that more than half of users reported experience of the following withdrawal symptoms individually for the first week after long-term/addictive dextromethorphan use: fatigue, apathy, flashbacks, and constipation. Over a quarter reported insomnia, nightmares, inability to feel pleasure, impaired memory, attention deficit and decreased libido. Rarer side effects included panic attacks, impaired learning, tremor, yellowing of the skin, hives and muscle pain. Frequent and long-term usage at very high doses could lead to toxic psychosis and other permanent psychological problems.[3]

Tolerance to many of the effects of DXM develops with prolonged and repeated use. This results in users having to administer increasingly large doses to achieve the same effects. After that, it takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption).

DXM produces cross-tolerance with all dissociatives, meaning that after the consumption of DXM all dissociatives will have a reduced effect.

Additionally, some users report an irreversible, permanent tolerance to DXM, which develops over a long period of time and is thought to correlate with the number of doses a person has ingested throughout their lifetime. Some users claim that there is a "50 trip limit", after which the rewarding and unique effects of DXM are said to disappear permanently. The reason for this is unknown, although it may be indicative of neurotoxicity.


Long-term dextromethorphan (DXM) abuse may result in a permanent irreversible tolerance due to several different mechanisms.

DXM is an NMDA receptor antagonist that blocks the inhibitory effects of glutamate in the brain. With repeated use, the body compensates for this blockade by increasing glutamate production. This leads to the rapid development of tolerance to DXM.[citation needed]

Chronic DXM abuse leads to neuroadaptations, including changes in neurons and synapses. These adaptive changes result in altered brain function that reduces the effects of DXM.[citation needed]

DXM exerts its effects by blocking NMDA receptors. Long-term abuse can lead to the downregulation of these receptors, meaning they are decreased in number. Reduced receptors result in diminished responsiveness to DXM.[citation needed]

DXM is metabolized in the liver. Chronic abuse can induce metabolic enzymes, which accelerate DXM breakdown.


Anecdotal evidence suggests that the risk of DXM overdose becomes significant at roughly 15mg/kg to 20mg/kg, or roughly 1000mg - 1500mg in a 70kg person.[citation needed] DXM overdose can have a wide range of effects, including delusions, hallucinations, psychosis, confusion, panic attacks, mania, sedation and severe balance issues, sometimes very inappropriate or violent behavior, increased heart rate, nystagmus and amnesia.[citation needed]

More serious side effects include anesthesia, respiratory depression[citation needed], dangerously high fever, risk of accidental injury, self-harm and seizures. Seizures are created possibly due to hyponatremia and a general lowering of the seizure threshold.[36] They are reported above the 900-1000mg dose range[citation needed]. It is possible that DXM may also affect other levels like potassium, vitamins or blood sugar further contributing to seizures and other health problems in a linear fashion in terms of severity and duration.

It is also believed that extremely high and repeated doses lead to serotonin syndrome.[citation needed]

One should not disrupt a person undergoing this experience as their delusions may cause them to respond with violence. Care should be taken as to not let the user get injured, and medical attention, or at the very least, medical surveillance should be sought to prevent severe respiratory depression, choking or organ damage.

Death from DXM toxicity is rare, although most overdose cases do cite life-threatening complications, typically extremely elevated heart rate and blood pressure, urinary retention and rhabdomylosis. Fever and seizures can lead to brain cell death.[37]

Dangerous interactions

Warning: Many psychoactive substances that are reasonably safe to use on their own can suddenly become dangerous and even life-threatening when combined with certain other substances. The following list provides some known dangerous interactions (although it is not guaranteed to include all of them).

Always conduct independent research (e.g. Google, DuckDuckGo, PubMed) to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions have been sourced from TripSit.

  • Benzodiazepines - Small doses of benzodiazepines can end a bad trip, however, both substances potentiate the ataxia and sedation caused by the other. This can lead to unexpected loss of consciousness at high doses. While unconscious, vomit aspiration is a risk if not placed in the recovery position.
  • Cannabis - CBD is known to be an inhibitor of the CYP2D6 enzyme, which normally breaks down DXM to Dextorphan. This can lead to unexpected effects.[38]
  • DOx - The DOx class as psychedelic stimulants have the potential to mask the effects of DXM and could lead to redosing to an unsafe level. DXM can also potentiate DOx resulting in an unpleasantly intense experience. DOx are also very physically stimulating and can cause heart rate and blood pressure problems especially since both substances have a very long duration.
  • 25x-NBOMe
  • 2C-T-x - As most 2C-T-x's are MAOIs this can potentially lead to serotonin syndrome, among other dangerous effects.
  • 5-MeO-xxT - Little information exists about this combination.
  • Amphetamines - Both substances raise heart rate, in extreme cases, panic attacks caused by these drugs have led to more serious heart issues.
  • Bupropion - Bupropion is a potent inhibitor of CYP2D6, the enzyme primarily responsible for breaking down DXM. This can lead to different and prolonged effects due to excessive accumulation of DXM in the bloodstream.[39] Recreationally mixing Bupropion with DXM can lower the seizure threshold, heighten anxiety/paranoia and increase the potential of tachycardia among other symptoms.[40] Information on this interaction within recreational doses is overall lesser-known and is to be advised against.
  • Cocaine - Both substances raise heart rate, in extreme cases, panic attacks caused by these drugs have led to more serious heart issues.
  • ΑMT
  • PCP - Due to PCP's unique pharmacology affecting dopamine levels this may cause cardiovascular complications.
  • MDMA - High risk of serotonin syndrome due to the fact that both MDMA and DXM are both serotonergic substances.
  • Alcohol - Both substances potentiate the ataxia and sedation caused by the other and can lead to unexpected loss of consciousness at high doses. Place affected patients in the recovery position to prevent vomit aspiration from excess. Additionally CNS depression can lead to difficulty breathing. Avoid on anything higher than 1st plateau.
  • GHB - Both substances cause ataxia and bring a risk of vomiting and unconsciousness. If the patient falls unconscious while under the influence there is a severe risk of vomit aspiration if they are not placed in the recovery position. This combination is hard to predict
  • GBL - Both substances cause ataxia and bring a risk of vomiting and unconsciousness. If the patient falls unconscious while under the influence there is a severe risk of vomit aspiration if they are not placed in the recovery position. This combination is hard to predict
  • Opioids - Both substances can, with heavy doses, cause respiratory depression, and additionally, extremely heavy doses of both may be hepatotoxic. Additionally, use of NMDA antagonists such as dextromethorphan can lower tolerance to and potentiate opioids, increasing their effects.
  • Tramadol- Both substances can, with heavy doses, cause respiratory depression and if heavy doses are taken both may be hepatotoxic. Additionally, if one takes DXM, their tolerance of opiates goes down slightly, thus causing additional synergistic effects.
  • MAOIs - High risk of serotonin syndrome.
  • SSRIs - High risk of serotonin syndrome.
  • Antihistamines - Many H1 antagonists, including antihistamines such Benadryl or terfenadine, as well as many antipsychotics, can slow down the metabolism of DXM due to their inhibition of CYP2D6, leading to possible death. [41]

Other interactions

  • DXM has been shown to prevent and reverse morphine tolerance while also increasing analgesic effects[42][43][44] as well as potentiating the analgesic activity of NSAIDs, naproxen, piroxicam, etodolac, diclofenac, and ketorolac.[45]

Legal status

DXM is available either over the counter or by prescription in most countries. Some countries require the purchaser to be over 16, 18 or 21.

  • Austria: Dextromethorphan is not listed in the "Suchtmittelgesetz" (Federal Law on Narcotics). Sales of DXM containing medications are restricted to pharmacies. DXM containing preparations are available at pharmacies without a prescription.[citation needed]
  • Canada: Dextromethorphan is listed as specifically exempt from the Controlled Drugs and Substances Act.[46] It is available OTC in Canada and can legally be obtained in powder form.
  • China: Dextromethorphan is a controlled substance("第二类精神药品") since July 1,2024[47].Sales of DXM containing medications are restricted to hospitals.
  • Denmark: The only product containing dextromethorphan in Denmark, Dexofan brand tablets, is a prescription type A medication.[48]Template:Better source needed
  • Finland: Dextromethorphan is listed in the medicinal product list and can only sold in pharmacies.[49] It can be brought without a prescription and at any age.
  • Germany: Dextromethorphan is not listed in the "Betäubungsmittelgesetz" (Federal Law on Narcotics).[50] Sales of DXM containing medications are restricted to pharmacies.[51] DXM containing preparations are available at pharmacies without a prescription.
  • Mexico: Dextromethorphan is not listed in the General Health Law (Ley General de Salud),[52] which specifies which substances represent a risk to public health. It is also listed in the Reference Medicine Listing[53] as a General Health Law article 226 fraction VI drug, which means it can be freely sold even in businesses that are not legally registered as pharmacies. In practice, this translates into DXM-only syrups being available off-the-shelf and without prescription at any supermarket with a pharmacy section.
  • Russia: Dextromethorphan is a schedule III controlled substance.[54]
  • Sweden: Dextromethorphan is a controlled substance (narcotics class V)[55][56], and is no longer marketed in Sweden due to drug abuse and associated risks. The cough medicine Tussidyl, with DXM as active ingredient, was withdrawn from Swedish sales in 1999.[citation needed]
  • Switzerland: Dextromethorphan is listed as a "Abgabekategorie B" pharmaceutical, which generally requires a prescription (it can also be given under advice from a pharmacist). Before being reclassified along other pharmaceutics in 2018, it was listed in category C, which meant it could be purchased over the counter.[57]
  • Poland: Dextromethorphan is over-the-counter drug, from 2016 it is possible to buy only one box of the drug in one pharmacy[58]
  • United States: Dextromethorphan is available over the counter and can be found in grocery stores, convenience stores, and online. Many physical locations requires the purchaser to be over the age of 18, however this is not the law.

See also

External links



  1. Siu, A., Drachtman, R. (2007). "Dextromethorphan: a review of N-methyl-d-aspartate receptor antagonist in the management of pain". CNS drug reviews. 13 (1): 96–106. doi:10.1111/j.1527-3458.2007.00006.x. ISSN 1080-563X. 
  2. Dicpinigaitis, P. V., Morice, A. H., Birring, S. S., McGarvey, L., Smith, J. A., Canning, B. J., Page, C. P. (April 2014). Sibley, D. R., ed. "Antitussive Drugs—Past, Present, and Future". Pharmacological Reviews. 66 (2): 468–512. doi:10.1124/pr.111.005116. ISSN 0031-6997. 
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  51. AMG - nichtamtliches Inhaltsverzeichnis 
  54. Постановление Правительства РФ от 30.06.1998 N 681 “Об утверждении перечня наркотических средств, психотропных веществ и их прекурсоров, подлежащих контролю в Российской Федерации” (с изменениями и дополнениями), ГАРАНТ 
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