Foods toxic to dogs: chocolate, grapes, xylitol and what to do if your dog eats them

Some of the most dangerous foods for dogs are things most households keep on the bench or in the fruit bowl. Unlike hazards that cause mild stomach upset, a small number of common foods can cause organ failure or death — even in a single ingestion. The ASPCA Animal Poison Control Center (APCC) lists toxic food ingestion as one of the top five reasons for animal poison calls annually.

This article covers the toxins with the strongest evidence base and the most serious consequences, based on the Merck Veterinary Manual, VCA Animal Hospitals, and ASPCA APCC toxicology resources. It also tells you what to do in the first minutes after suspected ingestion — because time matters.

Chocolate: theobromine and caffeine

Chocolate contains two methylxanthines — theobromine (the primary toxin) and caffeine. Dogs metabolise theobromine much more slowly than humans, allowing it to accumulate to toxic levels. Toxicity is dose-dependent and varies by chocolate type.

• Dark chocolate: approximately 400–1500 mg theobromine per 100g — highest risk
• Milk chocolate: approximately 150–200 mg theobromine per 100g — significant risk, especially in small dogs
• White chocolate: negligible theobromine — lowest risk, but not zero
• Baking/cooking chocolate: up to 1500 mg per 100g — very high risk
• Cocoa powder: up to 2300 mg per 100g — extremely dangerous even in small quantities

Clinical signs include vomiting, diarrhoea, restlessness, excessive urination, racing heart, muscle tremors, and seizures. Onset is typically 6–12 hours after ingestion. Fatality can occur with severe ingestion, particularly in small dogs and puppies.

Grapes and raisins: unpredictable acute kidney failure

Grapes, raisins, sultanas, and currants (including dried versions in baked goods) can cause acute kidney failure in dogs. The toxic mechanism is not fully understood; research has pointed to tartaric acid as a candidate compound, but the mechanism has not been conclusively established as of 2025. Critically, the toxic dose is unpredictable — some dogs develop kidney failure after eating one or two grapes; others appear unaffected by larger amounts. Because there is no safe known threshold, any grape or raisin ingestion should be treated as a potential emergency.

• Signs: vomiting and diarrhoea within 24 hours; lethargy, loss of appetite, abdominal pain, decreased urination as kidney failure progresses
• Timeline: kidney failure can develop within 24–72 hours
• Treatment: decontamination (induced vomiting, activated charcoal) if very recent ingestion; intravenous fluids; monitoring kidney values
• Prognosis: depends on dose and how quickly treatment begins — early intervention significantly improves outcomes

Xylitol: hypoglycaemia and liver failure

Xylitol is a sugar alcohol used as a sweetener in sugar-free gum, some peanut butters, baked goods, vitamins, medications, and dental products. It is well tolerated by humans but causes a massive insulin release in dogs, leading to severe hypoglycaemia (low blood sugar) within 30–60 minutes of ingestion, though some gum formulations may delay onset up to 12–18 hours. At higher doses it causes acute liver failure.

• Signs of hypoglycaemia: weakness, vomiting, loss of coordination, collapse, seizures
• Signs of liver failure: jaundice, vomiting, lethargy — may appear 12–24 hours later
• Dose for hypoglycaemia: as low as 0.1g/kg; xylitol content per gum piece varies by brand and product — always check the label
• Products to check: sugar-free gum and mints, some peanut butters (check label), sugar-free ice cream, vitamins, some oral hygiene products

Onions, garlic, leeks and other Alliums

All members of the Allium family — onions, garlic, leeks, chives, shallots — cause oxidative damage to red blood cells in dogs, leading to haemolytic anaemia. Garlic is roughly five times more concentrated in thiosulfate than onion. Importantly, cooked Alliums are just as toxic as raw ones, and cumulative exposure matters — a dog fed small amounts of onion in cooking over weeks can develop toxicosis.

Other high-risk foods: a summary

• Macadamia nuts: weakness, hyperthermia, tremors — mechanism unknown; not usually fatal but requires monitoring
• Alcohol: dogs have very low tolerance; even bread dough (which ferments to alcohol in the gut) is dangerous
• Caffeine (coffee, tea, energy drinks): similar mechanism to theobromine; can cause cardiac arrhythmias
• Raw yeast dough: rises in the stomach (causing bloat) and produces alcohol as a fermentation by-product
• Salt (in large quantities): sodium ion poisoning; excessive thirst, vomiting, diarrhoea, seizures
• Nutmeg: myristicin causes CNS depression, tremors, seizures at higher doses
• Cooked bones: can splinter and perforate the gastrointestinal tract — not a toxin, but a serious emergency

What to do if your dog eats a toxic food

• Note the time, the food, and a quantity estimate (how many pieces of gum, how much chocolate)
• Call your vet or a 24-hour emergency clinic immediately — do not wait for symptoms
• Do NOT induce vomiting unless a vet tells you to: some substances cause more damage on the way back up
• Bring the packaging if you can — the vet may need to check the ingredient list (especially for xylitol)
• Keep the number of your nearest emergency vet in your phone now, before you need it