Why?

Caffeine is a methylxanthine alkaloid that acts as a central nervous system stimulant in all mammals, but dogs metabolize it far more slowly than humans. Caffeine inhibits adenosine receptors and phosphodiesterase, causing accelerated heart rate, increased blood pressure, and central nervous system excitation that can progress to seizures.

The danger comes from concentration. A single espresso contains ~64mg of caffeine — enough to cause serious symptoms in a 10-lb dog, whose toxic threshold is approximately 20mg/kg. Coffee grounds and used tea bags contain concentrated caffeine and are frequently chewed by curious dogs. Energy drinks combine caffeine with other stimulants, amplifying the risk.

Dark chocolate + coffee (common in mocha desserts) creates a compound methylxanthine emergency — both toxins add to total exposure.

How much is dangerous?

Mild symptoms begin at approximately 20mg caffeine per kg of body weight. Severe toxicity and death can occur at 150mg/kg. A standard 8oz cup of coffee contains 80–100mg of caffeine.

What are the symptoms?

ONSET:Signs typically appear within 1–2 hours of ingestion.
  • restlessness and hyperactivity
  • rapid or irregular heart rate
  • muscle tremors
  • seizures
  • hyperthermia
  • excessive panting
  • vomiting
  • cardiac arrhythmias

What should I do?

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Call your vet or ASPCA Poison Control (+1 888-426-4435) immediately. Inducing vomiting may be recommended if ingestion was recent. Hospitalization for cardiac monitoring and seizure management may be needed.

Frequently asked questions.

Can dogs drink decaf coffee?

Decaf still contains small amounts of caffeine (2–15mg per cup). While a small lick is unlikely to cause harm, there's no reason to offer coffee to a dog.

What about tea?

Tea contains caffeine — black tea has 40–70mg per cup, green tea 20–45mg. Treat tea the same as coffee.

My dog ate coffee grounds — is that worse?

Much worse. Coffee grounds contain highly concentrated caffeine. Even a tablespoon of used grounds can cause toxicity in a small dog. Emergency vet visit required.

Disclaimer: This information is for educational purposes only and does not constitute veterinary advice. Every dog is different. Always consult your veterinarian before making changes to your dog's diet or in the event of a potential poisoning emergency.