If you have begun giving your cat amoxicillin and you see your cat having one or more of the above symptoms, contact your veterinarian. Once the veterinarian has treated your cat’s immediate symptoms and your cat is stabilized, he will ask you about any specific symptoms your cat is having and when they began. It will be very helpful to take the medication to the veterinarian with you, as in a case of an amoxicillin allergy, he would have begun showing signs after taking the medication. Your veterinarian may recommend that you have your cat tested to determine the source of the allergen.
Before this is done, however, your medical professional will take a few laboratory tests, such as blood work, urinalysis, and biochemistry profile to check his organs and how they are functioning. This will allow your veterinarian to rule out any underlying illnesses. Your veterinarian may then perform skin tests on your cat to see where the allergen is coming from.
The doctor will apply a few items to the cat’s skin using a very thin needle. The needle will scratch the surface of the skin while applying a specific allergen. More than likely, your veterinarian will use a serum with amoxicillin on the skin test to see how the skin reacts. If your cat is having an amoxicillin allergy, he will have a reaction on the skin. Typically, the reaction will be a red bump or hives on the skin. He may also choose to check for other allergens as well; this will be discussed between you and the doctor.
If your veterinarian is concerned that your cat does, in fact, have an amoxicillin allergy, he will have you discontinue the use of the medication. He may prescribe an alternate antibiotic in its place.