There are many substances commonly available in the human world that are poisonous and can prove lethal to your pet. Always contact your vet immediately if you suspect your pet has ingested anything that could do them harm. Never watch and wait, many symptoms can take hours or days to manifest and by that time it could be too late.

Common Human Food and Drink which is Poisonous for Dogs


Chocolate contains a stimulant called Theobromine (similar to caffeine) that is poisonous to dogs. The amount of Theobromine differs in different types of chocolate – dark chocolate has the most in it and white chocolate has very little.Theobromine mainly affects the heart, central nervous system and kidneys. Symptoms will occur from 4-24 hours after your dog has eaten chocolate and will vary depending on the amount of chocolate (Theobromine) your dog has eaten.

Click here for more information on the symptoms of chocolate poisoning.


Onions are toxic to dogs and cats. Worryingly signs of poisoning occur a few days after consumption and so you may not be immediately aware of what is making your pet ill.

All forms of onion will make your pet ill including dried/dehydrated, raw and cooked onions, so be particularly careful when disposing of leftovers such as pizzas, Chinese and Indian food and even baby food often contains puréed onion.

The onion family causes gastrointestinal upset and may result in red blood cell damage, you should be particularly careful to keep these out of animal’s reach.

Grapes and raisins

These fruits can be extremely dangerous to dogs and the signs and symptoms may not become apparent for up to 5 days after consumption. Grapes and raisins can cause kidney failure and are extremely dangerous to your pets. Contact your vet if you suspect they have eaten them, even if your pet seems fine.

Macadamia nuts

Macadamia nuts cause dogs to experience weakness, depression, tremors, vomiting and reduces their ability to maintain their body temperature and they may overheat. Symptoms typically last for 12 to 48 hours.


Alcohol is significantly more toxic to dogs than to humans and could cause vomiting, diarrhoea, decreased coordination, depression of the central nervous system, shaking, difficulty breathing, abnormal blood acidity, coma and even death.


Dogs are more sensitive to the effects of caffeine than people and large quantities can cause similar problems to chocolate toxicity.

Corn on the cob and sweetcorn

Dogs are unable to easily digest corn on the cob and it often results in gastrointestinal blockage and causes constipation, vomiting and can make them very ill.


Xylitol is an artificial sweetener found in many foods such as sugar-free gum, diabetic cakes and diet foods. This substance causes many animals to release insulin which can cause a potentially fatal lowering of their blood sugar (hypoglycaemia). Symptoms include; lethargy, vomiting, loss of coordination, an inability to stand up and seizures. Xylitol has also been linked to fatal acute liver disease and blood clotting disorders in dogs. Even very small amounts can be extremely dangerous so contact your vet immediately if you’re worried.


Cooked bones are particularly dangerous for dogs as the bones become brittle and can splinter causing choking or possibly puncturing further down the digestive tract. Small bones can get stuck in their bowel and often cause constipation.


Avocados contain a substance called Persin which can give dogs diarrhoea or make them vomit.


Milk and milk products can cause diarrhoea as dogs struggle to break down lactose.


Sugar coated Ibuprofen tablets are very appealing to dogs – if you suspect they have eaten them you need to get immediate veterinary help. Symptoms include vomiting, diarrhoea, bleeding from the gut, stomach ulceration and kidney failure.


Tip : Always take the packaging and remains of poisonous foods with you to the vet as this will help them to estimate how much has been ingested and establish exactly what it was and if there is an antidote.



First Aid for Pets provides this information for guidance and it is not in any way a substitute for veterinary advice. The author does not accept any liability or responsibility for any inaccuracies or for any mistreatment or misdiagnosis of any person or animal, however caused. It is strongly advised that you attend a practical First Aid for Pets course or take our online course to understand what to do in a medical emergency.

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