Microplastics and Misinformation: What Science Really Says
November 12, 2025
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Brand Name :
Delsym
(United States) [Available] ,GoodSense Cough DM Childrens
(United States) [Available] ,Cough DM
(United States) [Available]Synonyms :
dextromethorphan
Class :
Antitussives
Brand Name :
Delsym
(United States) [Available] ,GoodSense Cough DM Childrens
(United States) [Available] ,Cough DM
(United States) [Available]Synonyms :
dextromethorphan
Class :
Antitussives
Adult:
Dosage Forms & Strengths:
Capsule-as hydrobromide
15 mg
Gel-as hydrobromide
7.5 mg/5 mL (120 mL)
Liquid-as hydrobromide
12.5 mg/5 mL (118 mL)
7.5 mg/mL (30 mL)
7.5 mg/5 mL (118 mL)
15 mg/5 mL (118 mL)
Lozenge-as hydrobromide
5 mg (10 ea)
Strip-as hydrobromide
7.5 mg (14 ea, 16 ea)
Suspension-ER
30 mg/5 mL (89 mL)
Pediatric:
Dosage Forms & Strengths:
Capsule-as hydrobromide
15 mg
Gel-as hydrobromide
7.5 mg/5 mL (120 mL)
Liquid-as hydrobromide
12.5 mg/5 mL (118 mL)
7.5 mg/mL (30 mL)
7.5 mg/5 mL (118 mL)
15 mg/5 mL (118 mL)
Lozenge-as hydrobromide
5 mg (10 ea)
Strip-as hydrobromide
7.5 mg (14 ea, 16 ea)
Suspension-ER
30 mg/5 mL (89 mL)
may increase the vasopressor effect
it may diminish the therapeutic efficacy when combined with castor oil
it may diminish the metabolism when combined with ciclesonide
Combining dextromethorphan with pranlukast may cause a reduction in the dextromethorphan’s metabolism
The potential for increased CNS depression risk or seriousness occurs when dextromethorphan is used together with pinazepam
The potential for increased CNS depression risk or seriousness occurs when dextromethorphan is used together with pipecuronium
When dextromethorphan is used together with medazepam, the risk or seriousness of CNS depression is enhanced
The potential for CNS depression may enhanced when dextromethorphan is used together with fencamfamin
Combining tegafur with dextromethorphan can reduce tegafur’s metabolism
When dextromethorphan is used together with niaprazine, the risk or seriousness of CNS depression is enhanced
When chlordiazepoxide is used together with dextromethorphan, this leads to enhanced risk or seriousness of CNS depression
When encainide is used together with dextromethorphan, this leads to a reduction in the encainide’s metabolism
When dextromethorphan is used together with melitracen, this leads to enhanced risk or seriousness of CNS depression
When emylcamate is used together with dextromethorphan, this leads to enhanced risk or seriousness of CNS depression
When indisulam is used together with dextromethorphan, this leads to a reduction in dextromethorphan metabolism
When dextromethorphan is used together with profenamine, this leads to enhanced risk or seriousness of adverse events
it may increase the risk of adverse effects of memantine
it may increase the risk of adverse effects of memantine
may increase the serotonergic effects
may increase the serotonergic effects
may increase the serotonergic effects
may increase the serotonergic effects
may increase the serotonergic effects
may increase the serotonergic effects
may increase the serotonergic effects
may increase the serotonergic effects
may increase the serotonergic effects
It may enhance the risk of adverse effects when combined with biologic agents
It may enhance the risk of adverse effects when combined with biologic agents
It may enhance the risk of adverse effects when combined with biologic agents
an alteration in the therapeutic activity of either of the drugs may be seen
Dextromethorphan acts primarily as a low-affinity, uncompetitive antagonist of NMDA receptors and as an agonist of sigma-1 receptors. It also exhibits antagonistic activity at α3/β4 nicotinic receptors. While these receptor interactions are known, the exact mechanism by which they produce dextromethorphan’s clinical effects remains
Adverse drug reactions:
Frequency not defined:
Dizziness
Drowsiness
Nervousness
restlessness
Gastrointestinal distress
Nausea
stomach pain
vomiting
There is no blackbox warning for dextromethorphan
Contraindicated in children under 4 years of age due to the risk of serious harm or death from misuse.
Do not use if you have taken a monoamine oxidase inhibitor (MAOI)—such as isocarboxazid, phenelzine, rasagiline, selegiline, tranylcypromine, or methylene blue—within the past 14 days, as life-threatening interactions may occur.
Use with caution in combination with other over-the-counter cough, cold, or allergy medications to avoid accidental overdose; check labels for duplicate ingredients.
Not effective for coughs caused by smoking, asthma, or emphysema—avoid use in these conditions unless advised by a healthcare provider.
Pregnancy warnings:
AU TGA pregnancy category: A
Breastfeeding warnings:
The release of the drug into the human breastmilk is unknown
Pregnancy Categories:
Dextromethorphan (DM) is a synthetic analog of codeine and a structural derivative of levorphanol, developed as a non-addictive alternative to morphine. Despite its structural similarity to opioids like morphine, it does not bind to mu-opioid receptors and lacks typical opioid effects.
Pharmacodynamically, DM exhibits non-competitive antagonism at NMDA receptors, agonism at sigma-1 receptors, and antagonism at α3/β4 nicotinic receptors. Its primary site of antitussive action is believed to be the nucleus tractus solitarius in the brainstem, which modulates the cough reflex. However, the exact mechanism by which it suppresses cough remains incompletely understood.
Pharmacokinetically, DM is lipophilic with an ionizable amine group, facilitating CNS penetration. It undergoes extensive first-pass metabolism in the liver, primarily via CYP2D6 to its active metabolite dextrorphan (DX), which is then glucuronidated to dextrorphan-O-glucuronide, the major plasma metabolite. DM is also metabolized by CYP3A4 to 3-methoxymorphinan.
Pharmacokinetics
Absorption
After a 30 mg oral dose, dextromethorphan reaches a Cmax of 2.9 ng/mL, with a Tmax of 2.86 hours and an AUC of 17.8 ng·h/mL.
Distribution
The volume of distribution is 5–6.7 L/kg, indicating extensive tissue distribution. Dextromethorphan is 60–70% bound to serum proteins.
Metabolism
CYP2D6 and CYP2C9 convert DM to dextrorphan (DX) via O-demethylation.
CYP3A4, CYP2D6, and CYP2C9 convert DM to 3-methoxymorphinan via N-demethylation.
DX and 3-methoxymorphinan are further metabolized to 3-hydroxymorphinan, then conjugated via O-glucuronidation or O-sulfation to inactive metabolites.
Elimination/Excretion
The specific route of elimination is not well defined, but metabolism plays a major role.
Half-life: The elimination half-life ranges widely from 3 to 30 hours, depending on individual metabolic capacity (e.g., CYP2D6 polymorphism).
Pharmacodynamics
Dextromethorphan is an opioid-related compound used in combination with other drugs to manage cough and pseudobulbar affect. It has a moderate therapeutic range, meaning that high doses may lead to intoxication. Its effects last for a moderate duration, and patients should be advised about the potential risk of overdose or misuse.
Dextromethorphan is primarily administered orally in various forms, including liquid syrups, capsules, oral strips, and lozenges. The typical adult dose is 10 mL (30 mg) every 4 hours, or 0.5 mg/kg up to 30 mg three to four times daily. For pseudobulbar affect (PBA), it is used in combination with quinidine (20 mg DM + 10 mg quinidine) in capsule form.
Generic Name: dextromethorphan
Pronounced: dex-troe-meth-OR-fan
Why do we use dextromethorphan?
Dextromethorphan is an over-the-counter cough suppressant that works by acting on the brain’s cough center. It is used to relieve coughs due to colds or flu, but is not effective for coughs caused by smoking, asthma, or emphysema. It is available alone or in combination with other medications.
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