Side Effects Dextromethorphan: Long Term And Short Term Negative Effects

Last Updated: December 18, 2019

The occurrence of side effects with proper use of DXM as prescribed by a doctor is very rare, and they do not constitute a threat. Less harmful side effects include nausea, vomiting, fever, dextromethorphan diarrhea, insomnia, and night sweats.

Hard side-effects are usually linked with abusing medicine for recreational purposes. Adverse reactions may appear while abusing all forms of this drug – syrup, tablets, caps, or pure DXM. Some abusers make DXM cold water extraction for getting pure form of a powder or crystals, and this method yields substances with higher potency and more adverse effects.

Dextromethorphan MOA relies on serotonin receptors, and in some cases, consumption of this medicine can induce serotonin syndrome. As the syndrome is potentially deadly, this constitutes one of the biggest DXM dangers. 

Dextromethorphan Side Effects

The exact type of adverse reactions depends on the DXM dose. Starting from low doses, and using an increasing amount of medication dextromethorphan side effects include:

  • insomnia
  • restlessness
  • mild nausea
  • constipation
  • nystagmus
  • mood swings
  • dizziness
  • blurred vision
  • confusion
  • sleepiness
  • itching
  • manic and hypomanic symptoms
  • euphoria-like states
  • behavioral inhibition
  • coma

Dextromethorphan Polistirex side effects are linked with longer absorption time, while this form of the drug starts working slowly, it also takes longer to wear down. This form of the chemical has modified release dosage (longer DXM half-life). Reactions such as the feeling of dissociation and disorientation might last even longer when compared with dextromethorphan HBr side effects.

dissociation and disorientation dxm side effects

While these reactions are visible and easy to notice, there are other less prominent dextromethorphan side effects, blood pressure, for instance. Hypertension, as well as hypotension, occur as a result of the ingestion of the drug, so individuals with cardiac problems, should keep this in mind. Dextromethorphan allergy is another possible adverse reaction, so be sure to read the manual before use.

DXM Short Term Effects

Most immediate short term effects of DXM effects of this drug are:

  • dilated pupils
  • dextromethorphan constipation
  • sleepiness (or even lethargy)
  • general loss of coordination
  • disorientation in space and time
  • slurred speech
  • other alcohol-like symptoms

Recreational use (“robotripping” or DXM trip) is often linked with the consumption of various other drugs (alcohol, amphetamines, etc.), which only aggravates dextromethorphan short term effects.

This medicine might also cause dry mouth, nose, or throat, profuse sweating, and “flushing”, which are frequent physiological reactions to the drug. Uncontrollable laughing, tongue biting, anhedonia, attention impairment, dysmnesia (memory problems) may also be observed.

DXM Long Term Effects

Long term effects of dextromethorphan cause an order of magnitude more negative reactions. The study on cognitive deterioration from long-term abuse warns that prolonged consumption of this cough syrup drug affects all aspects of cognitive functioning and may cause the next DXM abuse long term effects:

  • short and long term memory
  • problem-solving skills
  • reaction time
  • feeling “keyed up” or tense
  • nervousness and irritability
  • agitation
  • depression
  • emotional instability (which is so prominent sometimes, that long term abuse is mistakenly diagnosed as Bipolar Disorder)

These symptoms are linked with dextromethorphan brain damage.

Even though dextromethorphan drug type does less harm to the body than most other drugs (hence its popularity), chronic use is likely to cause liver damage.

Dextromethorphan in pregnancy correlates with a higher frequency of congenital disabilities and other long term adverse reactions that impact both the mother and the child.

Dextromethorphan Toxicity

DXM toxicity is the leading cause of side effects. The negative reactions on the brain are linked with neurotoxic properties of this chemical. DXM liver toxicity is usually the result of chronic consumption. Hepatotoxicity of this cough syrup means that the liver becomes unable to get rid of toxins. DXM cardiotoxicity is low and usually related to pseudoephedrine, which is often used together with medicine.

The other popular form of this medication, hydrobromide, is absorbed much faster, which means that dextromethorphan HBR toxicity will be expressed more abruptly and drastically.

The neurotoxicity of the medicine still needs to be proven, which is why it’s safe to say that dextromethorphan neurotoxicity isn’t one of the main side effects. The toxic effects are usually managed through moderate use. The medicine’s toxic properties are often revealed through DXM hangover.

DXM Poisoning

Dextromethorphan poisoning, at its severe, acute form, resembles psychotic decompensation and acute PCP-like intoxication. In lower doses are more insidious symptoms appear, which can absolutely not be perceived as symptoms of poisoning. The most common acute dextromethorphan poisoning symptoms are:

  • DXM headache (may last for several days)
  • drowsiness
  • delusions of persecution
  • auditory and visual hallucinations
  • incoherent speech
  • violent behavior
  • elevated temperature
  • cardiac dysfunctions
  • respiratory dysfunctions

feeling of dxm poisoning

DXM bromide poisoning is related to salts that sometimes contain hydrobromide form of this drug. This form of intoxication is usually manifested by:

  • strong headache
  • apathy and irritability
  • coma, in extreme cases

The Therapy and Rehabilitation for DXM Side Effects

Side effects of medication can be treated with a plethora of substance abuse treatment options. Cognitive Behavioral Therapy might help individuals with dextromethorphan depression. For more acute cases, like DXM psychosis (usually the result of mixing DXM and LSD), hospitalization is necessary.

Furthermore, many rehabilitation facilities treat chronic cases of dextromethorphan abuse. A combination of psychotherapy and institutionalization is advised for individuals that exhibit extreme symptoms of addiction.

Page Sources

  1. A Hinsberger, V Sharma, D Mazmanian. Cognitive deterioration from long-term abuse of dextromethorphan: a case report. 1994.
  2. Bridgette Martinak, Ramy A. Bolis, Jeffrey Ryne Black, Rachel E. Fargason, Badari Birur. Dextromethorphan in Cough Syrup: The Poor Man’s Psychosis. 2017.

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.


Leave a comment