Pholcodine
Pholcodine is a derivative of codeine that acts as an antitussive. It possesses mild sedating properties but lacks analgesic effects. It has a lower potential for inducing dependence compared to codeine. **Clinical Pearl:** It is primarily used for cough suppression where the underlying cause cannot be removed and the coughing is detrimental to the animal's health (e.g., chronic bronchitis, tracheal or mainstem bronchial collapse). > **Warning:** It is not effective for respiratory tract infections and is unlikely to be effective for kennel cough in dogs. Many over-the-counter adult human cough mixtures contain dextromethorphan or guaifenesin, which should be used with extreme caution or avoided in veterinary patients.
Mechanism: Pholcodine depresses the cough reflex by acting directly on the **cough centre** in the central nervous system (CNS) → suppression of the medullary cough center.
Dosing by species
- Cough suppression · 0.1-0.2 mg/kg · PO · q6h · As needed · Up to 4 times daily
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Respiratory depression
- Raised intracranial pressure
Adverse effects
- Sedation
- Constipation (less severe than codeine)
- Anaphylaxis (reported in humans)
Drug interactions
- Tramadol · Increased risk of CNS and respiratory depression · major
- Other opiates · Additive CNS and respiratory depression · major
Monitoring
- Respiratory rate and effort
- Level of sedation
- Fecal output (monitor for constipation)
Overdose
Overdose may result in exaggerated opiate effects, including severe **sedation**, **respiratory depression**, and potentially coma. Treatment is supportive; naloxone may be considered as an opioid antagonist if severe respiratory depression occurs.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.