If your dog is shaking, stumbling, panting hard or has had a seizure, stop reading and call your veterinarian or an emergency clinic now. In the US, the ASPCA Animal Poison Control Center (888 426 4435) and the Pet Poison Helpline (855 764 7661) answer around the clock; a consultation fee may apply.
The short version: most dogs show no signs at all for the first few hours. According to the Merck Veterinary Manual, signs usually begin 6 to 12 hours after eating, start with thirst, vomiting and restlessness, and in severe cases last up to 72 hours. That delay is the trap. Getting the chocolate back out works best soon after eating (Merck's example is within 2 hours), long before anything looks wrong.
Chocolate is consistently the number one reason people call the Pet Poison Helpline, and most of those calls are about dogs. The week of Halloween is when bowls of candy sit at dog height, so here is what each stage looks like.
The timeline at a glance
| Time since eating (approximate) | What you will usually see | What to do |
|---|---|---|
| 0 to 2 hours | Usually nothing | Work out the dose and call. This is when a vet can most easily make the dog vomit. |
| 2 to 6 hours | Often still nothing | Do not read calm as safe. Keep the wrapper and keep watching. |
| 6 to 12 hours | First signs: thirst, vomiting, diarrhea, bloated belly, restlessness | Any sign after a dose above 20 mg/kg means a vet call. |
| 12 to 24 hours | With larger doses: hyperactivity, peeing a lot, wobbling, tremors | Tremors or wobbling are a clinic visit, not a phone call. |
| 24 to 72 hours | Severe cases still affected; mild cases fading | Follow your vet's plan. Seizures at any point are an emergency. |
The hour bands are our rough guide built around Merck's 6 to 12 hour onset, not a published schedule. Every dog and every dose is different.
Hours 0 to 2: nothing to see, everything to decide
Right after the theft your dog will probably look normal, maybe pleased with itself. This is the most useful window you get. Merck gives induced vomiting within 2 hours of eating as its example for a dog that has no signs yet, and it only helps while chocolate is still in the stomach.
So the job in this window is arithmetic, not observation. Find the wrapper, work out how much is missing, and put your dog's weight, the amount and the type into the chocolate toxicity calculator. The result in mg per kg tells you whether to call:
- Under 20 mg/kg: below the level where Merck reports mild signs starting. Call your vet to confirm that watching at home is enough.
- 20 to 40 mg/kg: mild signs are possible. Call a vet now and describe the weight, the amount and the type.
- Over 40 mg/kg: Merck places heart effects at 40 to 50 mg/kg and seizures at 60 and above. Go to a clinic without waiting for signs.
Do not make your dog vomit at home unless a veterinarian tells you to. It can do more harm than the chocolate.
Hours 2 to 6: the quiet stretch
This is when owners relax too early. Theobromine and caffeine, the two compounds that do the damage, may still be working their way into the body, and the dog can look completely normal. If you have not called yet and the dose was above 20 mg/kg, call now: a vet can still help, and you will know what to watch for.
If the dose was low and your vet agrees you can watch at home, keep fresh water out and let your dog outside often. Write down the time it ate, so you can tell the vet exactly how long it has been if things change.
Hours 6 to 12: the first signs
Merck lists the first signs in this order: heavy thirst, vomiting, diarrhea, a swollen belly and restlessness. In practice you may notice your dog drinking bowl after bowl, pacing instead of settling, or vomiting brown, chocolate-smelling material.
Any of these after a dose above 20 mg/kg is a reason to call, even if the dog otherwise seems fine. Chocolate is also very fatty, and Merck notes that the fat alone can trigger pancreatitis in susceptible dogs, so repeated vomiting and a painful belly deserve a call even when the dose was low.
Hours 12 to 24: when it gets serious
With larger doses the signs escalate: hyperactivity, peeing much more than usual, a wobbly or drunk-looking walk, and muscle tremors, then seizures at the top of the range. A racing heartbeat sits behind many of these. If you put your hand on your dog's chest and the heart is hammering while it is lying down, that is part of the picture.
Tremors, wobbling or collapse mean a clinic visit now. Do not wait for the morning.
Day 2 and day 3: why it lasts so long
Dogs clear theobromine slowly. Merck gives a half-life of 17.5 hours in dogs, which means half of the dose is still in the body the next day:
| Hours after eating | Share of the dose still in the body |
|---|---|
| 17.5 | 50% |
| 35 | 25% |
| 52.5 | 12.5% |
| 72 | about 6% |
That is a simplification, because absorption takes time at the start, but it explains why severe cases can stay affected for up to 72 hours and why a dog that looked better in the evening can still be restless the next morning. Mild cases usually fade as the dose falls.
Signs that mean go now
- Seizures, collapse or stiffness
- Muscle tremors or a wobbly, drunk-looking walk
- A racing heartbeat at rest, or heavy panting that does not settle
- Any signs at all in a puppy, a senior dog, or a dog with heart disease or epilepsy
- Baking chocolate, cocoa powder or a high-percentage dark bar, whatever the dog looks like
If the dog is acting normal but you are not sure about the dose, read my dog ate chocolate but is acting fine. For the thresholds by weight and chocolate type, see how much chocolate is dangerous. Cats are covered in can cats eat chocolate.
FAQ
How soon after eating chocolate does a dog show signs?
Usually 6 to 12 hours, according to the Merck Veterinary Manual. A dog that looks fine one hour in has told you nothing yet.
What is usually the first sign?
Thirst, vomiting, diarrhea, a bloated belly and restlessness, in roughly that order. Vomit that smells of chocolate is a clear clue about what happened.
How long does chocolate poisoning last in dogs?
Mild cases fade as the dose clears. Severe cases can last up to 72 hours, because dogs clear theobromine so slowly that half of it is still in the body after 17.5 hours.
Can a dog die from eating chocolate?
Yes, at high doses. Merck puts the median lethal dose at 100 to 200 mg/kg. That takes a lot of milk chocolate but very little baking chocolate or cocoa powder, which is why the type matters as much as the amount.
How we made this article
Timeline, signs, doses and the 17.5 hour half-life come from the Merck Veterinary Manual, Chocolate Toxicosis in Animals (updated February 2026). The call statistic comes from the Pet Poison Helpline's Halloween page. The half-life table is our own arithmetic from Merck's figure. We are not veterinarians; this page does not say more than those sources, and sources for every formula on this site are on the methodology page. Checked on 11 October 2026.
This page is general information for a healthy adult dog and is not veterinary advice. When in doubt, call your veterinarian.