1. Contact your veterinarian immediately.
  2. Your veterinarian may instruct you to induce vomiting, however, do not induce vomiting unless instructed to.
  3. If possible, provide a sample of the product ingested, including any packaging and package inserts, to your veterinarian to aid in identification of the toxin and estimation of the dose received.




Onset of signs is usually within 6-8 hours of ingestion but slow release formulations may be associated with onset of clinical signs up to 72 hours following ingestion.

  • Depression
  • Dilated pupils (Mydriasis)
  • Rapid respiratory rate (tachypnoea)
  • Vomiting
  • Rapid heart rate (tachycardia)
  • Uncoordinated or wobbly gait (ataxia)
  • Hypersensitivity to touch (hyperaesthesia)
  • Respiratory distress
  • Agitation
  • Tremors
  • Seizures


Venlafaxine causes a huge increase in serotonin and noradrenaline levels and a small increase in dopamine levels.


Veterinary treatment may involve blood pressure monitoring and intravenous fluid administration, sedation for agitation, muscle relaxants and anti-seizure medication. If serotonin syndrome occurs, an antihistamine may be administered. Activated charcoal may be administered to reduce absorption of the drug.


BSAVA (2012) BSAVA/VPIS Guide to Common Canine and Feline Poisons. Gloucester: BSAVA.

Peterson ME (2011) Your cat ate what? Proceedings, Western Veterinary Conference 2011. Available online at www.vin.com

Pfizer Canada Inc (2012) Product monograph EFFEXOR(r) XR Capsules (Venlafaxine hydrochloride) Extended Release Capsuls (37.5, 75, 150mg), available online at www.pfizer.ca