🫁 Antitussive

Dextromethorphan Dosage Calculator for Dogs

Veterinary-guided dextromethorphan (DXM) dosing for dogs with chronic nonproductive cough — including xylitol product warnings and combination drug safety checks.

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XYLITOL WARNING: Many OTC cough syrups (e.g., Robitussin) contain xylitol, which is severely toxic to dogs. ONLY use pure dextromethorphan products with NO xylitol, alcohol, guaifenesin + other decongestants. Read every ingredient label before use.

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About Dextromethorphan (DXM)

Drug Class

NMDA Receptor Antagonist — Cough Suppressant and Analgesic Adjunct

Mechanism of Action

Dextromethorphan is an NMDA glutamate receptor antagonist and sigma-1 receptor agonist. At antitussive doses, it suppresses the cough reflex centrally. At higher doses used in neuropathic pain, it modulates central sensitisation. It is metabolised to dextrorphan which has opioid activity.

Primary Uses in Dogs

Non-productive cough suppression (kennel cough, tracheal collapse, post-bronchoscopy). Adjunct analgesic for neuropathic or chronic pain states. NOT for productive coughs where expectoration is beneficial.

Dosing Quick Reference

Indication Dose Frequency
Cough suppression 0.5–1 mg/kg q6–8h PO
Pain adjunct 1–2 mg/kg q8h PO (vet supervised)
Maximum dose 2 mg/kg q8h

Common Side Effects

  • Sedation and drowsiness
  • Ataxia and disorientation at higher doses
  • Nausea or vomiting
  • Increased heart rate
  • Serotonin syndrome risk when combined with SSRIs/MAOIs

Monitoring

Monitor for sedation and ataxia, particularly in small dogs. Reduce dose if excessive sedation is noted.

⚠️ Never use combination cough products containing other ingredients (especially xylitol, decongestants, or antihistamines) — give plain DXM only. Do not combine with MAOIs (selegiline). Many OTC human products also contain guaifenesin or acetaminophen — always check the label before giving to a dog.

What Is Dextromethorphan in Dogs?

Dextromethorphan (DXM) is a non-opioid antitussive that acts on sigma-1 receptors and NMDA glutamate receptors in the medullary cough centre. In veterinary medicine it is occasionally used for chronic nonproductive cough in dogs (e.g., kennel cough, collapsing trachea), though its efficacy in dogs is considered modest compared to butorphanol or hydrocodone.

DXM is extensively metabolised via CYP2D6 to dextrorphan, which has greater NMDA receptor activity. Dogs metabolise DXM more rapidly than humans, resulting in shorter duration of action. It is available as 15 mg and 30 mg tablets, and syrups of variable concentration (verify label carefully).

Important Limitations

  • Evidence for efficacy in dogs is limited; butorphanol is more effective for cough suppression
  • NOT appropriate for productive cough (may trap secretions)
  • Avoid in dogs on MAO inhibitors or serotonergic drugs (serotonin syndrome risk)
  • Many combination OTC products contain harmful ingredients — never use multi-symptom products

How to Use This Calculator

  1. Confirm your product contains ONLY dextromethorphan (no xylitol, alcohol, pseudoephedrine, or phenylephrine)
  2. Enter your dog’s weight
  3. Enter the DXM concentration of your product
  4. Click Calculate to see dose range
  5. Always confirm with your vet before administering

🧮 Dextromethorphan Dose Calculator

Dextromethorphan Dosing

References

  1. Plumb DC. Plumb’s Veterinary Drug Handbook, 9th ed. Wiley-Blackwell; 2018.
  2. Papich MG. Saunders Handbook of Veterinary Drugs, 4th ed. Elsevier; 2016.
  3. ASPCA Animal Poison Control Center. Xylitol toxicity in dogs. 2023.