The short answer
- Not safe in any amount. Grapes (red, green, seedless, peeled), raisins, sultanas and Zante currants are all risky. Raisins are dried grapes, so a handful packs many fruits into a small amount.
- The damage hits the kidneys. Severe cases stop producing urine. Most dogs that reach that stage die or are put to sleep, even with treatment.
- Early treatment works well. A dog that is treated before signs appear usually does far better than one brought in once it is sick.
Why grapes are toxic to dogs
For years the cause was unknown. The current explanation, described by the ASPCA Animal Poison Control Center and in the Merck Veterinary Manual, is tartaric acid. Dogs appear to lack the transporters other species use to clear this acid from their kidney cells, so it builds up there and damages the tubules that filter the blood.
The tartaric acid content differs between grape varieties, growing conditions and ripeness. That explains the puzzling part: the same dog may eat grapes once without trouble and be poisoned the next time. Tamarind, which is also rich in tartaric acid, has been linked to the same kind of kidney injury. True currants (the Ribes berries used in some jams) have not.
How many grapes are dangerous?
There is no proven safe amount. As a rough guide, the Merck Veterinary Manual says that more than one grape or raisin per 10 lb (4.5 kg) of body weight may contain enough tartaric acid to put the kidneys at risk. The table applies that guide to common dog sizes. It is not a safe limit: dogs below these numbers still need a call to the vet.
| Dog's weight | Possible kidney risk above |
|---|---|
| 5 lb (2.3 kg) | half a grape or raisin |
| 10 lb (4.5 kg) | 1 grape or raisin |
| 20 lb (9 kg) | 2 |
| 40 lb (18 kg) | 4 |
| 60 lb (27 kg) | 6 |
| 80 lb (36 kg) | 8 |
| 100 lb (45 kg) | 10 |
Based on the rough guide of one grape or raisin per 10 lb of body weight in the Merck Veterinary Manual. Count raisins, not handfuls: even a small snack box holds dozens of them.
Where grapes and raisins hide
- Raisin bread, cinnamon raisin bagels, hot cross buns, fruit cake and mince pies
- Trail mix, granola, muesli, cereal bars and oatmeal cookies
- Fruit salad, grape juice, jams and jellies made from grapes
- Chocolate-covered raisins: two hazards at once (check the chocolate toxicity calculator as well)
- Tamarind candy, tamarind paste and dishes made with it
Signs of grape poisoning in dogs
| Time after eating | What you may see |
|---|---|
| 6–12 hours | Vomiting (often with pieces of grape or raisin), diarrhea |
| 12–24 hours | Lethargy, no appetite, belly pain, weakness, dehydration, drinking more, tremors |
| 24–72 hours | Kidney failure: little or no urine, then collapse |
Blood tests show the kidney damage as a rise in creatinine, often before the dog looks very sick. Signs that come and go are no reason to wait: once a dog stops producing urine, it is unlikely to survive without dialysis.
What to do if your dog ate grapes or raisins
- Take away anything left and keep the packaging.
- Estimate how many grapes or raisins are missing and when your dog ate them.
- Call your vet, an emergency vet or a poison hotline right away, even if your dog seems fine and even if it was only one or two.
- Do not induce vomiting at home unless a vet tells you to. Hydrogen peroxide and salt can cause their own injuries.
- If the vet asks you to come in, go right away.
At the clinic, a vet will usually make your dog vomit if it ate recently. If a large amount was eaten or your dog already has diarrhea, the next step is intravenous fluids for at least 48 hours to protect the kidneys, with blood tests to check kidney values. Dogs that stop producing urine need specialist care such as dialysis.
Frequently asked questions
Can dogs eat grapes?
No. Grapes, raisins and Zante currants can cause sudden kidney failure in dogs. The amount that harms a dog varies a lot between fruits and between dogs, so no amount is known to be safe.
My dog ate one grape. What should I do?
Call your vet, an emergency vet or a pet poison hotline now, even if your dog seems fine: ASPCA Animal Poison Control at (888) 426-4435 or Pet Poison Helpline at (855) 764-7661. For a small dog, one grape can already be above the level the Merck Veterinary Manual describes as a possible kidney risk. Do not make your dog vomit unless a vet tells you to.
How many grapes can kill a dog?
There is no reliable number. The Merck Veterinary Manual says more than one grape or raisin per 10 lb (4.5 kg) of body weight may pose a kidney risk, but the toxic substance varies between fruits. Most dogs that develop complete kidney shutdown die or are put to sleep, so every exposure should be treated as an emergency.
Why are grapes toxic to dogs?
Tartaric acid is the leading explanation. Dogs appear unable to clear it from the kidney cells that handle organic acids, so it builds up and damages them. Its content varies between grapes, which is why some dogs eat grapes without harm and others go into kidney failure.
How long after eating grapes will a dog get sick?
Most affected dogs vomit or have diarrhea within 6 to 12 hours. Kidney failure, with little or no urine, can follow within 24 to 72 hours. Treatment works best before signs appear.
Sources
- Merck Veterinary Manual: Grape, Raisin, and Tamarind (Vitis spp, Tamarindus spp) Toxicosis in Dogs, by Cristine Hayes, DVM, ASPCA Animal Poison Control Center (reviewed September 2024): tartaric acid, dose guide, timing of signs, treatment and prognosis.
- ASPCA Animal Poison Control Center and Pet Poison Helpline (contact numbers, checked October 2026).
This page is for general information only and does not replace a veterinarian. Dogs react very differently to grapes and raisins, and a small amount does not mean your dog is safe. If your dog ate grapes or raisins, contact a vet or a pet poison hotline. Last updated: October 2026.