Common Medicines That Are Toxic to Cats



As a dedicated veterinarian, it is our responsibility to ensure the health and well-being of our feline patients. However, it is crucial to be aware that certain medicines can have toxic effects on cats. Cats possess unique sensitivities and physiological differences compared to other animals, making it essential for veterinarians to exercise caution when prescribing medications. In this comprehensive guide, we will delve into the details of six common medicines that can be harmful to cats, equipping you with the knowledge necessary to make informed treatment choices and prioritize feline safety.


1. Acetaminophen (Napa):


Acetaminophen, known as paracetamol in some countries, is widely used to alleviate fever and pain. Unfortunately, this medication can pose severe risks to our feline friends. Cats lack a specific enzyme necessary to metabolize acetaminophen properly, resulting in its accumulation and subsequent toxicity. Even a minute dosage of 10 mg/kg can have detrimental effects. Symptoms of acetaminophen toxicity in cats encompass increased respiratory rate, pale mucous membranes, hypothermia, tachycardia, CNS depression, anorexia, vomiting, edema, diarrhea, coma, and, in extreme cases, death.


2. Lily Toxicity:


While not a medication, it is essential to highlight the dangers of certain lilies, including Easter lilies, tiger lilies, Asiatic hybrid lilies, and daylilies. Even a small ingestion of these flowers or their leaves can prove fatal to cats. The toxic compounds within these lilies can cause severe damage to the feline kidneys. Early signs of lily toxicity include salivation, vomiting, and anorexia, progressing to polyuria/polydipsia, dehydration, and eventually renal failure.


3. Phosphate Enemas (Anema DS):


Phosphate enemas are frequently administered to relieve constipation in humans. However, when used on cats, they can lead to tragic consequences. Many cat owners, with the best intentions, may unknowingly administer these enemas to their constipated feline companions. Phosphate enemas contain sodium phosphate and biphosphate, which can result in severe electrolyte imbalances in cats. Signs of toxicity manifest as lethargy, ataxia, miosis, arrhythmias, muscle tremors, and even seizures.


4. Bismuth Subsalicylate (Peptocid):


Bismuth subsalicylate, commonly used to treat diarrhea, poses a significant risk to cats. Cats have a deficiency in glucuronosyltransferase, an enzyme responsible for metabolizing salicylate. As a result, even moderate doses of bismuth subsalicylate can cause toxicity. Lethargy, vomiting, diarrhea, hematemesis, melena, abdominal pain, and severe gastric ulceration are clinical signs of bismuth subsalicylate toxicity in cats.


5. Meloxicam (Melocam):


Meloxicam, an NSAID commonly used for pain and fever management, was once believed to be safe for feline use. However, adverse events, including renal failure and death, have been associated with its oral suspension formulation. As a precautionary measure, it is now recommended for one-time post-surgical injection only, avoiding the risk of potential complications.


6. Benzocaine Toxicity (Orogel):


Benzocaine, a topical anesthetic, can be toxic to cats if absorbed through the skin or ingested. Cats exhibit heightened susceptibility to methemoglobinemia caused by benzocaine. Within minutes of application or ingestion, cats may experience significant methemoglobinemia, resulting in a reduced capacity to carry oxygen.


 In addition, benzocaine can induce Heinz body hemolytic anemia. Decontamination and bathing are crucial if skin absorption occurs, and GI tract decontamination may be necessary in cases of ingestion.




In the pursuit of feline well-being, it is vital for veterinarians and pet owners alike to recognize the potential dangers certain medicines can pose to cats. By understanding the toxic nature of medications such as acetaminophen, lilies, phosphate enemas, bismuth subsalicylate, meloxicam, and benzocaine, we can make informed decisions that prioritize feline safety. Cats are unique creatures with distinct sensitivities and requirements, and their health should always be treated with utmost care and consideration. By avoiding the use of these toxic medicines, we can protect our feline companions and promote a safer and healthier environment for them. Remember, knowledge is the key to safeguarding our feline friends and ensuring their long, happy lives.