Side Effects of Pet Medications 2025: Vet Approved Overview 💊🐶

By Dr. Duncan Houston BVSc

🔍 Why Medication Risks Matter

All medications carry potential risks. When vets prescribe drugs, we weigh benefits—like pain relief and infection control—against possible adverse reactions. Proper dosing, duration, and monitoring minimize harm.

🛡️ NSAIDs (Pain & Inflammation) – Rimadyl, Metacam, Deramaxx, Galliprant

• Common side effects: vomiting, diarrhea, reduced appetite, lethargy.
• Serious issues: GI ulcers/perforation, liver or kidney damage, clotting changes, jaundice, incoordination, seizures.
• Use caution in older dogs, dehydrated pups, or those with liver/kidney disease or on steroids/concurrent NSAIDs.
• Monitoring: Baseline bloodwork before long-term use, followed by periodic checks every 6–12 months.

🧪 Antibiotics – Doxycycline, Cephalexin, Metronidazole

• GI upset (vomiting, diarrhea), appetite loss—usually mild.
• Neurological effects with metronidazole—lethargy, ataxia, seizures—rare, dose-related.
• Allergic reactions ranging from rash to anaphylaxis, microbiome imbalance and resistance risk.
• Avoid self-medicating with human antibiotics; always follow vet instructions.

🩺 Corticosteroids – Prednisolone / Dexamethasone

• Short-term side effects: increased thirst & urination, hunger, panting, lethargy, GI upset.
• Long-term use concerns: GI ulcers, delayed healing, diabetes, Cushing's-like symptoms, muscle weakness, potential heart issues and immune suppression.
• Monitoring: Regular checks on blood glucose, liver function, and blood pressure for chronic users.

💉 Opioids – Tramadol, Codeine

• Side effects: sedation, constipation, slowed breathing, mood changes anxiety.
• Used mainly short‑term; monitor respiratory rate and stool output closely.

🐛 Heartworm & Parasite Drugs – Ivermectin, Milbemycin (Heartgard), Isoxazolines

• Heartworm preventives rarely cause issues; overdose risk exists—watch for vomiting or neurological signs.
• Isoxazoline-class tick/flea drugs (Bravecto, NexGard): risk of rare neurologic events; avoid in dogs with seizure history.

⚠️ Dangerous Human Medications

• NSAIDs (ibuprofen, aspirin, naproxen): GI bleeding, renal failure—even in small doses.
• Acetaminophen: toxic—even low doses can cause liver failure and anemia.
• Sedatives (Ambien): confusion, respiratory depression—cases of accidental poisoning are rising.
• ⚠️ Keep all human meds strictly out of reach and separate from pet meds.

✅ Safe Medication Practices

1. Administer only vet-prescribed medicines, at correct dosages.
2. Follow label—give with or without food as directed.
3. Give full antibiotic courses to prevent resistance.
4. Store meds securely—away from pets and children.
5. Report any side effects—like vomiting, behavioral changes, abnormal labs—to your vet immediately.
6. Routine monitoring (blood/urine tests) for long-term NSAID, steroid, and diabetic medications.

📋 Dr Houston’s Medication Safety Checklist

• ✔️ Know every drug your pet ingests (incl. OTC and supplements)
• ✔️ Understand possible side effects before starting medication
• ✔️ Use dosage tools (pill organizers, reminders) for accuracy
• ✔️ Monitor appetite, toileting, behavior, breathing, energy daily
• ✔️ Schedule recommended lab tests during long-term therapy
• ✔️ Store meds safely and separately from human prescriptions
• 📱 Contact Ask A Vet or your clinic at any early side effect sign

🌟 Final Thoughts

Medications are powerful tools—but even safe ones can carry risks. Understanding side effects—from mild GI upset to serious organ damage—and maintaining open communication with your vet ensures your dog reaps benefits while minimizing harm. Always follow vet instructions, monitor closely, and store medicines safely. 🐾❤️

Need help managing your dog’s meds, side effect signs, or monitoring plans? Visit AskAVet.com or download the Ask A Vet app for personalized veterinary support anytime. 📱🐶