Toxic human foods

Can cats be poisoned by human food? This month, iCatCare’s Keeping Cats Safe campaign is highlighting the potential risk (albeit small) that some human foods may pose to cats. Dogs, because they often consume large amounts of these foods, are more frequently affected.

Chocolate, especially dark and milk chocolate, can be toxic to cats 

Some human foods are a potential risk to pets, although severe poisoning in cats is rarely reported. Cats may eat human foodstuffs through inquisitiveness or by being fed inappropriate food by owners and, of course, food is often readily available in the home or left unattended or improperly stored. Cats also investigate shopping bags, fruit bowls or waste bins. Children too can try feeding all sorts of food to cats!


The alcohol in beers, wines and spirits is ethanol, and ethanol is also found in surgical spirit and alcohol hand gel. Cases of ethanol poisoning in cats and even dogs are rarely reported. The effects of ethanol are the same in animals as they are in humans. Ethanol is a central nervous system depressant and onset of signs is rapid (within 1–2 h). There is often vomiting (which may have an odour of alcohol), diarrhoea, excitability and agitation, and then depression, disorientation, vocalisation and drowsiness. In severe cases, which are rare in cats (probably because they do not drink very much), there may be coma, hypothermia, urinary incontinence and respiratory depression. In recovery from a significant exposure the cat is likely to be depressed and lethargic (hungover). Affected animals are given supportive treatment and monitoring by the vet.


Theobromine is found in chocolate and is toxic to most animals, but there is limited information on the toxic dose of chocolate in cats. The lethal dose of milk chocolate for an average sized (4 kg) cat would be around 560 g and for dark/plain chocolate, it would be around 140g; however, lower doses can still cause signs of poisoning. White chocolate contains less theobromine and therefore is less likely to cause poisoning. Signs of theobromine poisoning include vomiting, diarrhoea, drinking a lot, lethargy, disorentation, depression or hyperactivity.

In more severe cases, which are rare in cats, there may be rapid breathing, diarrhoea, tremors, convulsions and arrhythmias of the heart.

Allium species

The allium group of plants includes leek, garlic, onion, spring onions and chives. These are present in many foods including soups, baby foods, seasonings, stock cubes, sauces and marinades, chutneys, pickles, ready-made meals and many spicy products. Cooking of these plants does not reduce toxicity.

Allium poisoning in cats is relatively rare and it may be that cats do not find onions palatable. Poisonings have occurred following the ingestion of soups and meals with meat flavourings as the main constituent. This can result in anaemia in the cat. Effects can occur from a single large dose or smaller repeated dosing. 

 The signs of allium poisoning are variable. Signs may occur suddenly within 24 h if a large quantity has been eaten, but it is more common for signs to occur after several days. Cats may have no appetite, vomit or show abdominal discomfort and diarrhoea. The breath may smell strongly of onions or garlic. Other signs that are associated with allium poisoning include anaemia, depression, lethargy, weakness, pale mucous membranes, fast heart beat and breathing. There may also be blood in the urine and it may have an onion odour. 

Vets will advise owners of cats known to have ingested food with allium content to ensure adequate hydration, to provide a high protein diet and to return if there is any sign of anaemia (pale mucous membranes, lethargy, weakness, dark urine) over the next few days. In severe cases, oxygen may also be required and a blood transfusion may be needed in a critically ill animal. 

grapes and sultanas
Grapes and sultanas can be poisonous to cats
mouldy food
Food waste in a compost bin can be a potential source of mycotoxins

Grapes and their dried fruits

Although renal failure from grapes and their dried fruits (sultanas, raisins and currants) is well recognised in dogs, there are also anecdotal cases of poisoning in cats. Signs of poisoning include vomiting, diarrhoea, bloody faeces, anorexia, tender abdomen, weakness and lethargy. There may be renal failure and cats with existing kidney problems may be more at risk of toxicity after ingestion of grapes and dried fruit. If the product involved is chocolate-coated raisins there is also a potential risk of chocolate toxicity.

Mouldy food

Some mouldy foods (including dairy products, bread, rice and fallen fruits and nuts), silage and compost contain mycotoxins from fungi that are toxic, but poisoning is rarely reported in cats and is much more common in dogs. It should be suspected in any animal with sudden onset tremors and a history of raiding a bin! Also fungal growth is most prevalent if the weather is warm and wet. 

Signs include vomiting, irritability, whole-body muscle tremors, panting, rapid heart rate and breathing, and, in severe cases, convulsions.

Veterinary treatment depends on severity but can include ensuring adequate hydration, monitoring respiration and temperature, cooling measures if required and ventilatory support in animals with severe respiratory depression. 


Potentially harmful foods are present in all households, although severe cases of toxicity in cats are rare.

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