A Vet’s Guide to Medication Side Effects in Pets 2025 🐾

By Dr. Duncan Houston BVSc

Hi, I’m Dr Duncan Houston BVSc, a veterinarian and founder of Ask A Vet. Every medication carries benefits—and risks. My aim? Help you navigate the most-used drug classes, understand their side effects, and use them **safely and confidently** with your pet. 🩺🐶

1. Common Medications & Side Effects

🐾 NSAIDs (Like Rimadyl, Metacam, Galliprant)

• Side effects: GI upset (vomiting, diarrhea, ulcers), kidney or liver issues, bleeding issues, and yellow eyes.
• Higher risk: With steroids—avoid simultaneous use, always include a washout.
• Vet tip: Always dose per veterinary guidance, maintain hydration, monitor kidneys, liver, and clotting.

💉 Antibiotics (Metronidazole, Fluoroquinolones, Penicillin)

• Neurological: Metronidazole can cause seizures, tremors—usually reversible.
• GI reactions: Vomiting, diarrhea, and appetite loss are common with penicillin and others.
• Vet tip: Monitor for neurological signs; switch meds under vet guidance if needed.

🧴 Flea/Tick Preventatives (Isoxazolines, Pyrethroids)

• From PetMD: Can trigger scratching, tremors, seizures, and collapse; especially harmful in breed-sensitive dogs like Collies.
• Vet tip: Always follow dose instructions; never use cat products for dogs; monitor high-risk breeds closely.

💊 Anti-Anxiety & Behavioral Meds (Fluoxetine, Clomipramine)

• Side effects: Lethargy, decreased appetite, GI signs, shakiness, restlessness, low blood pressure.
• Vet tip: Begin with low doses, schedule follow-up, and monitor potently during introduction.

📦 Corticosteroids (Prednisone, Triamcinolone)

• Risks: GI ulcers, immune suppression, weight gain, increased thirst, and urination. Severe when combined with NSAIDs.
• Vet tip: Taper steroids as directed; avoid unsupervised combinations.

💉 Immunosuppressants (Atopica®, Mycophenolate)

• Side effects: GI upset, lethargy, bloating, gingival overgrowth, and infections.
• Vet tip: Give on an empty stomach if advised; watch for side effects, especially in the first weeks.

🤕 Pain Relievers (Metoclopramide, Imodium)

• Side effects: Metoclopramide can cause tremors/restlessness; Imodium may lead to constipation or serious GI issues and breed-specific reactions.
• Vet tip: Use short-term and always check for drug interactions.

2. Monitoring & When to Worry

• ⚠️ GI signs: Vomiting, diarrhea, black/tarry stool, loss of appetite
• 🧠 Neurological: Tremors, seizures, incoordination
• 🫀 Cardiovascular: Collapse, weakness, pale gums
• 🩺 General: Excessive thirst/urination, skin changes, jaundice

If you notice these, contact your vet immediately. Discontinue only if instructed.

3. Safe Medication Practices

• ✅ Always confirm dose, timing, interactions with your vet.
• 📑 Understand washout periods—especially when switching NSAIDs or combining steroids.
• 🌡 Store meds appropriately and out of reach.
• 📆 Monitor long-term meds with periodic bloodwork for organ health.

4. Vet-Approved Tools & Enrichment

Support pet care with these:

• Ask A Vet App – access telehealth for side-effect check-ins and prescription guidance without delay.

5. Case Example: NSAID Overdose

Case: Bella, a senior lab, ingested an extra dose of Rimadyl
Bella became lethargic, vomited, and her gums turned pale within hours. Emergency care included IV fluids, gastroprotectants, and monitoring. She recovered fully over 48 hours. Lesson: Keep medications secure and follow dosing instructions carefully.

6. 100% Vet‑Approved Final Insights

• Every medication comes with risk—awareness and monitoring are essential.
• Know the side effects of your pet’s medications—contact vet immediately if signs appear.
• Use tools like Ask A Vet’s telehealth service for side effect support.
• Keep routine bloodwork in place for long-term meds.
• All medication changes or multi-drug regimens must be guided by a vet.

📌 Final Thoughts from a Vet

Medications are invaluable, saving countless lives—but they require respect and vigilance. With the right knowledge, monitoring, and access to veterinary guidance, you can ensure that your pet benefits safely from treatment. If you're ever in doubt, Ask A Vet is here for expert support. 💊❤️