Dextromethorphan

A widely used cough suppressant that acts on the brain’s cough center.

What is Dextromethorphan?

Dextromethorphan (DXM) is a centrally acting antitussive (cough suppressant) commonly used in cough syrups and cold medications.

It reduces the urge to cough without affecting mucus production.

History & Background

Dextromethorphan was developed as a safer alternative to codeine. Unlike opioids, it lacks significant pain-relieving and addictive properties at therapeutic doses.

Chemical Structure & Properties

• IUPAC name: 3-methoxy-17-methylmorphinan
• Molecular formula: C₁₈H₂₅NO
• Molar mass: 271.4 g/mol
• Functional groups: Ether, tertiary amine

Dextromethorphan is the dextrorotatory isomer of levorphanol, giving it cough-suppressing effects without opioid analgesia.

Mechanism of Action

Dextromethorphan acts on the medullary cough center in the brain by:

• Suppressing cough reflex
• NMDA receptor antagonism (at higher doses)
• Sigma-1 receptor stimulation

Pharmacokinetics

• Absorption: Rapid oral absorption
• Peak plasma time: 2–3 hours
• Metabolism: Liver (CYP2D6)
• Half-life: 3–6 hours
• Excretion: Urine

Medical Uses

• Dry cough
• Non-productive cough
• Cold-related cough
• Influenza-associated cough

Dosage Guidelines

Adults: 10–20 mg every 4 hours

Extended-release: 30 mg every 6–8 hours

⚠️ Do not exceed 120 mg/day.

Side Effects

• Dizziness
• Nausea
• Drowsiness
• Confusion (high doses)

Warnings & Precautions

• Avoid alcohol
• Risk of abuse at high doses
• Use caution in liver disease

Drug Interactions

• MAO inhibitors
• SSRIs (risk of serotonin syndrome)
• Other CNS depressants

Frequently Asked Questions

Is dextromethorphan an opioid? – No.

Does it cause sleep? – Mild drowsiness may occur.

Is it addictive? – Only at abusive doses.

Can children take it? – Only as prescribed.

⚠️ Educational content only. Not a substitute for professional medical advice.