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Paracetamol/Tylenol (acetaminophen) Poisoning in Cats

paracetamol (acetaminophen) poisoning in cats

Also known as acetaminophen (common brand names include Tylenol, Panamax, and Panadol), paracetamol is an over the counter pain medication used to control minor pain and reduce fever in humans. It is extremely toxic to cats as they lack the necessary liver enzyme (

As little as 10 mg/kg is enough to kill a cat.

Ingestion either happens when well-intentioned owners administer the medication to their cat either directly or indirectly administers another medication (such as cold and flu medications or cough syrup, which shouldn't happen unless a veterinarian has said it's okay to do) which has paracetamol in it. I should note, this is a common cause of paracetamol poisoning in humans too, and care must be taken when using more than one type of medication at a time, to make sure you are not doubling up. It is possible for a cat to eat paracetamol, but less common than with dogs as cats are much more discriminate in what they eat.

The medication can cause a life-threatening condition known as methemoglobinemia (metHb) which is an increase in the production of methemoglobin, a form of haemoglobin which is unable to function as an oxygen carrier, resulting in a lack of oxygen to the organs and tissues.  Toxic levels of waste products of metabolism (known as metabolites) build up, causing liver failure. In addition to liver damage and methemoglobinemia, Heinz body anemia also occurs, in which the red blood cells are destroyed due to the presence of Heinz bodies.

What are the symptoms of paracetamol poisoning in cats?

As we have noted, the damage is threefold, the liver fails, the cat slowly asphyxiates (starved of oxygen) and anemia occurs due to Heinz body anemia.

Typical symptoms include:

As liver begins to fail, jaundice (yellowing of the skin and gums) and mental disturbances may occur.

How is it diagnosed?

A history of exposure to the medication, plus accompanying symptoms such as brown coloured gums. Your veterinarian may wish to run some tests to determine the extent of the damage. These may include complete blood count and biochemical profile to look for methemoglobinemia and evaluate liver enzymes.

How is it treated?

The faster your cat is treated, the better. If ingestion is recent then vomiting will be induced followed by administration of activated charcoal to absorb the toxins.

  • N-acetylcysteine (NAC) is a form of the amino acid "cysteine". This amino acid assists in the detoxification and elimination of paracetamol which protects further damage to the liver.

  • Vitamin C can help speed up the removal of paracetamol.

  • Blood transfusions may be required for cats with severe anemia.

  • Oxygen therapy.

  • Fluid therapy.

Prognosis depends on how quickly your cat is treated after ingestion and how much medication was consumed.

Never administer medications to your cat without veterinary supervision. Over the counter or prescription painkillers should never be given to cats as most of them are unsuitable and can result in death. If you think your cat is in pain, he should be taken to a veterinarian immediately.

Also see:

Aspirin poisoning in cats