When a dog starts throwing up while on prednisone, it can be alarming. Vomiting can indicate that your dog’s body is reacting poorly to the medication — or that another underlying condition is being affected by the steroid.
We outline the common causes of vomiting in dogs taking prednisone, what you can do at home, and when to seek veterinary help.
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Dog Throwing Up on Prednisone — Why It Happens
Vomiting while your dog is on prednisone often points to stomach irritation, dosage sensitivity, or an existing illness being aggravated by the medication.
Prednisone is a powerful corticosteroid that can affect multiple body systems, including the digestive tract. When used improperly or at high doses, it can upset the stomach lining, increase acid production, and lead to nausea or vomiting.
In some cases, the vomiting isn’t directly from prednisone but from an underlying issue that’s being masked or worsened by it, such as pancreatitis, liver disease, or infection.
Common Causes of Dog Throwing Up on Prednisone
1. Stomach Irritation and Ulcers
Prednisone increases stomach acid and decreases the protective mucus layer in the gut. This can cause gastritis or even ulcers in sensitive dogs.
You might notice your dog throwing up yellow bile, eating grass, or refusing food. These are signs of an upset stomach, and the longer it continues, the higher the risk of dehydration.
This side effect is especially common if prednisone is given on an empty stomach or combined with NSAIDs like Rimadyl or Metacam. Always give prednisone with food unless your vet instructs otherwise.
Read more: Dog Diarrhea Prednisone (Steroid side effects on digestion)
2. High Dosage or Rapid Dose Changes
Dogs are sensitive to steroid dosing. Too much prednisone or a sudden increase can overwhelm the digestive system, leading to nausea and vomiting.
If your dog’s dose was recently adjusted, the vomiting may be a temporary reaction as the body adapts. However, if it continues beyond 48 hours, call your vet — it could signal that the dosage is too strong or that tapering is needed.
3. Pancreatitis
Prednisone can sometimes trigger or worsen pancreatitis, especially in dogs that are overweight or have a high-fat diet. Pancreatitis causes inflammation of the pancreas, leading to vomiting, lethargy, abdominal pain, and loss of appetite.
If your dog is throwing up repeatedly and acting tired or hunched, pancreatitis may be to blame. This condition requires immediate veterinary care — delaying treatment can be dangerous.
4. Liver or Kidney Stress
Because prednisone is processed through the liver and kidneys, these organs can become strained over time. This can cause nausea, vomiting, and a loss of appetite.
Older dogs and those already on other medications are especially vulnerable. Regular blood tests help monitor these organs while your dog is on steroids. If vomiting occurs along with yellowing eyes or gums, that may signal liver involvement.
5. Drug Interactions
Prednisone can interact with many medications — including antibiotics, antifungals, and pain relievers — that amplify side effects like vomiting.
For instance, combining prednisone with NSAIDs (like carprofen) dramatically increases the risk of stomach ulcers. Always inform your vet about every medication and supplement your dog is taking before starting prednisone.
6. Hidden Infection or Underlying Condition
Prednisone suppresses the immune system. While that helps control inflammation, it can also make infections worse or harder to detect.
If your dog starts vomiting while on prednisone, it could mean there’s an infection brewing — such as a urinary tract infection, gastrointestinal infection, or even something systemic. Fever, fatigue, or diarrhea along with vomiting may confirm this possibility.
Read more: Dog Diarrhea After Prednisone (What it means and when to worry)
What to Do If Your Dog Is Throwing Up on Prednisone
If your dog vomits shortly after taking prednisone, first make sure they have access to water but don’t force them to eat right away. Wait a few hours before reintroducing food, offering a small, bland meal like boiled chicken and rice.
Always give prednisone with food to protect the stomach. Avoid fatty or rich foods, which can worsen nausea.
If vomiting happens repeatedly, contact your vet. Never stop prednisone suddenly — it must be tapered down to prevent dangerous adrenal withdrawal. Your vet might reduce the dose, change the timing (e.g., give it at night), or switch to a different anti-inflammatory drug.
You can also ask your vet about prescribing a stomach protectant such as omeprazole or famotidine. These help reduce acid and protect the stomach lining during prednisone therapy.
Monitor hydration carefully. Dehydration can occur quickly in vomiting dogs, especially small breeds. Check for dry gums, sunken eyes, or reduced urination.
When to Call or Visit Your Vet
If your dog vomits more than twice in 24 hours or can’t keep food or water down, it’s time to call the vet.
Seek immediate veterinary care if vomiting is accompanied by:
Weakness or collapse
Blood in vomit or black, tarry stools
Yellowing of the eyes or skin
Severe abdominal pain or bloating
Trembling or excessive panting
Even if the vomiting seems mild, prolonged nausea can interfere with prednisone absorption, making the treatment less effective. Your vet can determine whether to adjust the dosage, prescribe an antacid, or switch to an alternative steroid like dexamethasone.
Read more: Dog Not Eating And Prednisone (Here’s what could be happening)
Key Takeaway
Vomiting while on prednisone is a common but concerning reaction that can point to stomach irritation, high dosage, or a deeper medical issue. Always give prednisone with food, never change the dose without your vet’s advice, and watch for signs of dehydration or pain.
With proper monitoring, most dogs tolerate prednisone well — but if vomiting persists, your vet can safely adjust the plan to protect your dog’s stomach and overall health.