Vet-Approved 2025 Guide: Monitoring Your Cat After Vaccines 🐱💉

By Dr. Duncan Houston BVSc

Vaccinations are a crucial part of keeping your cat healthy, protecting them against diseases like feline leukemia, rabies, and panleukopenia. While vaccines are generally safe, it’s important to monitor your cat for any reactions or side effects after their appointment. Most cats tolerate vaccines well, but vigilance ensures prompt action if anything unusual occurs.

1. Mild Reactions Are Normal

Some mild reactions are common and usually short-lived:

• Soreness or swelling at the injection site

• Mild fever

• Decreased appetite or temporary lethargy

These symptoms typically resolve within 24 to 48 hours and rarely require veterinary intervention. You can make your cat comfortable by providing a quiet, warm resting spot.

2. Watch for Lethargy

It’s normal for cats to be a bit tired or less playful after vaccination. However, if lethargy:

• Persists for more than 48 hours

• Is accompanied by other concerning symptoms

…contact your veterinarian. Prolonged lethargy could indicate an underlying reaction that needs attention.

3. Gastrointestinal Upset

Some cats may experience vomiting or diarrhea following a vaccine. Usually, this is mild and short-term. Signs to monitor include:

• Persistent vomiting or diarrhea

• Blood in vomit or stool

• Other symptoms such as lethargy or loss of appetite

If any of these occur, seek veterinary advice promptly.

4. Injection Site Lumps or Swelling

A small lump or swelling at the injection site can be normal. It should decrease in size within a few days. Seek veterinary care if you notice:

• Swelling lasting longer than a week

• Rapidly growing lumps

• Pain, heat, or redness at the site

Rarely, injection-site tumors (sarcomas) can develop, so monitoring is key.

5. Allergic Reactions (Rare but Serious)

Severe allergic reactions are uncommon but life-threatening. Symptoms include:

• Facial swelling or hives

• Difficulty breathing

• Sudden collapse or extreme lethargy

If you observe any of these signs, contact your veterinarian immediately or go to an emergency clinic.

6. Persistent or Worsening Symptoms

Even mild side effects should gradually improve. Contact your veterinarian if:

• Symptoms do not improve within a few days

• Any signs worsen over time

• Your cat shows unusual behavior or discomfort

Early intervention ensures your cat remains safe and healthy.

✅ Key Takeaways

• Most cats experience mild, temporary reactions after vaccination.

• Observe your cat closely for 24–72 hours post-vaccination.

• Seek veterinary advice for persistent, severe, or unusual symptoms.

• Always err on the side of caution—veterinarians are your best resource for ensuring your cat’s safety.

With careful monitoring and prompt attention to any concerning signs, your cat can enjoy the full benefits of vaccination safely.