Centrally acting cough suppressant
ATC code: R05DA09 (Dextromethorphan)
Brand names
Bisolvon Antitusivo, Romilar, Robitussin Tos, Delsym
The dextro-isomer of levomethorphan (opioid), but without analgesic or narcotic action. At therapeutic doses, selectively suppresses the medullary cough center without respiratory depression. At doses 10–30 times therapeutic, produces dissociative effects via NMDA receptor antagonism and serotonin reuptake inhibition – basis of recreational misuse. CYP2D6-metabolized to dextrorphan (active metabolite with greater NMDA activity).
Second line
Used in dry non-productive cough disturbing sleep or daily activity. ACCP 2018 and NG120 (2019) do not list central cough suppressants as first-line – modest efficacy data in acute cough (2014 Cochrane meta-analysis showed no significant advantage over placebo in adults). Adult dose 15–30 mg 3–4 times daily. Short course, no more than 7 days.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Dextromethorphan is a cough suppressant and NMDA-receptor antagonist. It is used for symptomatic treatment of dry cough during respiratory infections (AAFP 2020 and CDC guidelines). In biohacker circles, dextromethorphan is taken at high doses as an antidepressant and for altered states of consciousness with empathogenic effects. The issued a 2010 warning about severe side effects with abuse: serotonin syndrome (especially in combination with SSRI or MAOI antidepressants), psychosis, motor disturbances, and acetaminophen-related hepatotoxicity in combination products. High-dose dextromethorphan is a psychoactive substance with abuse potential. If dextromethorphan is being taken for mood or cognition, consider seeking a second opinion: for depression there are drugs with confirmed efficacy.
1 pair found. Sorted from critical to minor.
Mechanism
Linezolid is a reversible MAO inhibitor. Dextromethorphan is a weak serotonin reuptake inhibitor and sigma-1 agonist. The combination produces synaptic serotonin accumulation and serotonin syndrome.
Symptoms
Within hours of co-administration: agitation, confusion, tachycardia, hypertension, hyperthermia, tremor, myoclonus, hyperreflexia. Severe cases – seizures, coma, rhabdomyolysis.
Management
Avoid dextromethorphan for the linezolid course (typically 7–14 days). Alternative antitussives: guaifenesin or honey for nocturnal cough. If dextromethorphan was already taken, stop linezolid; serotonin syndrome resolves within 24 hours.
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Avoid in T1 where possible. For dry cough in pregnancy, first-line is non-pharmacological (hydration, humidification); paracetamol if fever is present.
Single doses are acceptable during lactation; regular use is not recommended.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Dextromethorphan is evaluated for the following indications with varying evidence strength: Dry cough (evidence tier C), Memory and concentration enhancement (evidence tier F). See the full indication matrix with dosing and citations above on this page.
Common side effects of Dextromethorphan (≥ 1 in 100): Drowsiness, Dizziness, Nausea, Dry mouth, Constipation. See the Safety section for uncommon and serious reactions.
FDA category C. Avoid in T1 where possible. For dry cough in pregnancy, first-line is non-pharmacological (hydration, humidification); paracetamol if fever is present.
Single doses are acceptable during lactation; regular use is not recommended.
Dextromethorphan is contraindicated in: Dextromethorphan hypersensitivity; Concurrent MAO inhibitors or within 14 days of stopping; Age under 6 (most OTC forms); Severe hepatic impairment; Respiratory failure. Full list in the Safety section.