When a dog is both vomiting and having diarrhea at the same time, the most likely explanation is that something irritated the stomach and intestines. This inflammation, called gastroenteritis, is usually caused by something your dog ate that didn’t agree with them. The good news is that most cases resolve on their own within 24 to 48 hours. But certain combinations of symptoms signal something more serious that needs veterinary attention right away.
The Most Common Cause: Something They Ate
Dogs are scavengers by nature, and the number one trigger for simultaneous vomiting and diarrhea is eating something they shouldn’t have. Garbage, table scraps, a dead animal found on a walk, grass, sticks, or simply too much food at once can all inflame the lining of the stomach and intestines. A sudden change in diet, like switching to a new brand of food without a gradual transition, does the same thing. In most of these cases, your dog’s body is doing exactly what it should: expelling the problem.
Food allergies can also cause recurring episodes. If your dog seems to get sick after eating the same type of food or treat repeatedly, the ingredient itself may be the issue rather than spoilage or overeating.
Toxic Foods That Cause Both Symptoms
Several common household foods are genuinely poisonous to dogs and trigger vomiting and diarrhea as early warning signs. Chocolate and caffeine cause nausea, vomiting, diarrhea, excessive thirst, and rapid breathing, typically within 6 to 12 hours of ingestion. Grapes and raisins produce vomiting in almost all cases, followed by diarrhea, weakness, and lethargy within the same timeframe. Left untreated, grapes can cause kidney failure.
Onions and garlic cause vomiting, diarrhea, abdominal pain, and depression. Avocado triggers gastrointestinal irritation and, in severe cases, respiratory distress. Even small amounts of alcohol can cause vomiting, diarrhea, poor coordination, and dangerously low body temperature. If you suspect your dog ate any of these, don’t wait for symptoms to worsen.
Infections and Parasites
Bacterial and viral infections of the gut cause vomiting and diarrhea that tends to be more persistent and severe than a simple dietary upset. Intestinal parasites, including roundworms, hookworms, and giardia, are another common culprit, especially in puppies or dogs that spend time around other animals.
Parvovirus is the most dangerous infectious cause. It’s most common in puppies and unvaccinated dogs, and it follows a recognizable pattern: lethargy and loss of appetite come first, followed by sudden high fever, then severe vomiting and bloody diarrhea. The virus destroys the cells lining the intestines, leaving the gut unable to absorb nutrients or keep bacteria from entering the bloodstream. Parvo is life-threatening and requires immediate veterinary care.
Intestinal Blockages
If your dog swallowed a toy, sock, bone fragment, or any object that can’t pass through the digestive tract, the result is a partial or complete blockage. The typical pattern is persistent vomiting (a dog that keeps throwing up but can’t keep anything down), loss of appetite, abdominal pain, weakness, and sometimes diarrhea. With a partial blockage, liquid stool may squeeze around the object while solid matter can’t pass.
Young dogs are especially prone to this. They’ll often still try to eat initially but vomit shortly after. A blockage won’t resolve on its own and can lead to intestinal rupture if untreated, so repeated vomiting after eating is a symptom worth taking seriously and quickly.
Other Medical Causes
Problems with the liver, kidneys, or pancreas can all produce vomiting and diarrhea as secondary symptoms. Heatstroke triggers both, along with heavy panting and disorientation. Stress, particularly from travel, boarding, or a major change in routine, can cause diarrhea on its own and occasionally vomiting too. Motion sickness is another straightforward explanation if the symptoms appeared during or right after a car ride.
A condition called acute hemorrhagic diarrhea syndrome (AHDS) causes a sudden onset of profuse bloody diarrhea, often described as resembling raspberry jam, along with vomiting, lethargy, and abdominal pain. It’s most common in small and toy breeds. The vomiting often starts before the bloody diarrhea appears. AHDS causes rapid, severe fluid loss that can lead to shock before obvious dehydration is even visible, so it requires emergency treatment.
Red Flags That Need a Vet Now
Not every episode of vomiting and diarrhea requires a vet visit, but certain signs mean you shouldn’t wait:
- Blood in the vomit or stool, whether bright red or dark and tarry
- Multiple episodes in a short period, especially if your dog can’t keep water down
- Lethargy or weakness beyond normal tiredness
- Swollen or painful abdomen when touched
- Known ingestion of something toxic or a foreign object
- Symptoms in a puppy, senior dog, or dog with existing health problems, since these groups dehydrate dangerously fast
The American Animal Hospital Association recommends seeking prompt veterinary care any time a pet has vomited multiple times in a short period or has severe diarrhea, especially alongside blood or other concerning signs.
How to Check for Dehydration
Vomiting and diarrhea together drain fluid fast. You can check your dog’s hydration at home by lifting their upper lip and looking at the gums. Healthy gums are pink and moist. Dry, sticky, or pale gums suggest dehydration. Press a finger against the pink area of the gum until it turns white, then release. The color should return to pink in less than two seconds. If it takes longer, your dog is likely dehydrated and needs fluids.
What to Do at Home
If your dog is otherwise alert, not in obvious pain, and the symptoms are mild, the standard first step is to remove all food and water. Don’t let your dog eat or drink anything until they’ve gone 6 to 8 hours without vomiting. This gives the stomach time to settle. After that window, start offering small amounts of clear liquids: water, an electrolyte solution like unflavored Pedialyte, or a similar rehydration drink.
Once your dog is keeping liquids down, introduce a bland diet. The classic recipe is boiled white rice mixed with plain boiled chicken breast (no skin, no bones, no seasoning). Cook the rice with three parts water to one part rice for 20 to 25 minutes until it’s very soft. Boil the chicken for 10 to 15 minutes until it pulls apart easily, then chop it finely. Mix about 2 cups of rice for every half cup of chicken. Feed small portions several times a day rather than one or two large meals.
Stay on the bland diet for a few days after symptoms stop, then gradually mix in your dog’s regular food over the course of three to five days, increasing the proportion of normal food at each meal. Jumping straight back to regular food too quickly often triggers a relapse.
Puppies and very old dogs are exceptions to the “wait and see” approach. They have smaller reserves of fluid and energy, and what starts as mild gastroenteritis can become a serious electrolyte imbalance quickly. For these dogs, even a single day of vomiting and diarrhea together warrants a call to your vet.