Norvasc Side Effects on Cats

Although Norvasc (amlodipine besylate) is a human drug, veterinarian Wendy C. Brooks says the calcium channel blocker is also a "popular" medication for treating high blood pressure in cats. High blood pressure is common in cats with kidney failure, hyperthyroidism, hypertrophic cardiomyopathy and other conditions, says Dr. Brooks, educational director for VeterinaryPartner.com. While Norvasc rarely causes side effects in cats, they do sometimes occur.

  1. Low Blood Pressure

    • Some cats on Norvasc may experience low blood pressure, or hypotension, according to veterinarian Dawn Ruben. Writing for the website PetPlace.com, she says symptoms of hypotension in cats include depression, weakness and fainting.

    Lethargy

    • A Norvasc patient information sheet prepared by the staff of Doctors Foster and Smith Pharmacy warns that the drug can cause lethargy in some cats.

    Loss of Appetite and Weight Loss

    • Some cats also experience loss of appetite and weight loss while taking Norvasc, according to the information sheet.

    Changes in Blood Values

    • Dr. Brooks says elevations in renal blood parameters and decreased blood potassium levels can both be side effects of Norvasc in cats.

    Reduced Heart Rate

    • Norvasc can reduce the strength of heart muscle contractions. While this is not usually cause for concern, according to Dr. Brooks, the drug should be used with caution for cats with a history of heart failure.

    Drug Interactions

    • Norvasc can cause interactions with aspirin, warfarin, furosemide, salix, propanolol, atenolol and other medications that also lower blood pressure, according to the Doctors Foster and Smith patient information sheet.

    Signs of Toxicity

    • The Norvasc patient information sheet lists staggering or dizziness, collapse and a slow heart rate as signs of toxicity or overdose in cats.