First 2 Hours: My Cat is Having an Allergic Reaction

Even in animals, allergic reactions can be serious.
Cats can be allergic to a wide number of things, from pollen to household cleaners. Like humans, cats can also experience allergic reactions ranging from minor to severe. It’s important never to underestimate an allergic reaction in your pet. So, what should you do if you think your cat is having an allergic reaction? The first few hours and in some cases, minutes, can be critical.
0-30 minutes in: Watch for Anaphylaxis
First, understand that any serious allergic reaction will typically happen within the first few minutes after exposure. The kind of reactions that can be life-threatening are usually systemic, after a particular allergen makes its way through your cat’s bloodstream. They often happen after a cat has eaten something, lapped something up, or been stung by something. If your cat is showing any of the following signs, she may be having an allergic reaction:
- Sneezing/coughing
- Itchy and/or watery eyes
- Swollen paws
- Vomiting or diarrhea
The above symptoms don’t necessarily indicate your cat is in need of urgent medical care, but should be monitored closely. If your cat is having any of the following symptoms, she could be experiencing a serious, even life-threatening allergic reaction known as anaphylaxis:
- Difficulty breathing
- Uncontrollable vomiting, bowel movements, and/or urination
- Collapse
- Lethargy (deep unresponsiveness)
- Seizure
If you suspect your cat may be suffering from systemic anaphylaxis, rush her to the closest emergency veterinarian as soon as possible. Do not wait! A vet may be able to administer drugs (like epinephrine or steroids) that can reverse the reaction and save her life.
30 minutes – 1 hour in: Call Your Vet
If you’re confident your cat’s life isn’t in immediate danger, keep monitoring her symptoms for signs of worsening then call the vet. Your vet will help you determine whether your cat should be seen by a professional or simply watched closely as the reaction dissipates. Your vet will likely ask you to recount anything your cat might have been exposed to. Think carefully about whether she may have eaten something new, been stung by an insect outdoors, ingested a chemical, or even started a new medication. Sometimes cats have allergic reactions to things they’ve been exposed to before without issue; allergies can develop later in life and when they do, they tend to be more serious each time the animal is exposed.
1 hour – 2 hours in: Look for Signs of Relief
Most allergic reactions will begin to show signs of dissipating after a few hours. If your cat doesn’t seem to be getting any better or in fact, seems to be getting worse, call the vet back to discuss your options. Although your cat may seem uncomfortable, do not give her any “human” medications without discussing with your veterinarian first. Many well-meaning pet owners give their cats Benadryl or other over-the-counter antihistamines to treat allergy symptoms only to inadvertently poison their pet. Do your best to keep your cat comfortable by creating a soothing environment and offering her plenty of water. If your cat’s allergy symptoms seem to come and go often (without getting worse each time), she’s likely allergic to something in the environment. This is particularly true if her symptoms are skin-related, such as swollen paws or a rash. Consider switching out environmental allergens such as bedding, carpet, or even your own fabric softener.