Also sold as Aldactone, Cardalis (with benazepril)
Vets prescribe this for dogs, so being on it is not a problem in itself. This page is about what happens when a dog gets more than it was meant to have.
Spironolactone is a diuretic used in dogs with heart disease, so a prescription for it is routine veterinary care. An overdose matters because it shifts potassium and fluid balance, which can show as weakness or an abnormal heart rhythm. Dogs already on heart medication are the ones most likely to reach a bottle of it. Keep the packet or prescription bottle: the strength and the number missing are what make the advice specific.
Educational reference. Not individualized veterinary advice.(more)
See this page's cited references for supporting information and our Sources page for the reference organizations we use. Citations do not imply that those organizations reviewed or endorsed DogSafe.
Part of Heart and blood-pressure medication on our medication safety hub.
Part of our guide to Human Medications and Dogs: The Complete A-Z of What's Dangerous.
Call the practice that prescribed it: they know the dose your dog is on, which is what decides whether this matters. Out of hours, either line below is open.
Available 24/7. A consultation fee may apply.
Exposure details to have ready
These are the questions a veterinarian or poison-control operator will ask. Fill in what you know and leave the rest blank. This tool does not estimate a dose or a risk score: medication risk depends on the exact ingredient, strength, and formulation, so the assessment has to come from the clinician on the call.
- Keep the package, blister pack, or prescription bottle. The strength and the full ingredient list are what make the advice specific.
- Do not induce vomiting unless a veterinarian or poison-control professional tells you to. It is the wrong move for several medications and can cause harm on its own.
- Do not give milk, food, salt, hydrogen peroxide, or any home remedy on your own.
- Do not give a second dose of anything to make up for one you think was missed.
- Count what is left in the packet, so the number missing can be worked out.
Your exposure summary
Read this down the phone or paste it into a message to your vet. It stays on your device; nothing here is sent to DogSafe.
Why Spironolactone needs caution
Spironolactone is a diuretic used in dogs with heart disease, so a prescription for it is routine veterinary care. An overdose matters because it shifts potassium and fluid balance, which can show as weakness or an abnormal heart rhythm. Dogs already on heart medication are the ones most likely to reach a bottle of it.
Part of the Human Medicine Exposures guide
For related dog-safety questions and product-by-product answers, see the complete human medicine exposures guide.
Signs to watch for
Most commonly vomiting, diarrhea, drooling, or mild sedation; less commonly unsteadiness or weakness after a large amount
Related items
Check the exact item or ingredient before assuming two similar exposures carry the same risk.
What to do next
Count the remaining tablets against what the prescription should have left, note the strength and the time, and call your vet's line with that number.
🚨Step-by-step: what to do in the first 10 minutes →Available 24/7. A consultation fee may apply.
Spironolactone for dogs: prescribed use and accidental doses
Two different questions bring people here: whether a vet may prescribe spironolactone to a dog, and what to do when a dog has swallowed some. The answers are not the same, so this page keeps them apart.
1. Start with the exact item
Spironolactone is a diuretic used in dogs with heart disease, so a prescription for it is routine veterinary care. An overdose matters because it shifts potassium and fluid balance, which can show as weakness or an abnormal heart rhythm. Dogs already on heart medication are the ones most likely to reach a bottle of it. Browse the complete human medicine exposures guide →
2. Check the details that change the answer
Record the amount, time, dog weight, and any missing packaging or plant parts. A clear label or photo prevents a look-alike from driving the decision. What to do in the first 10 minutes →
3. Use related pages before making assumptions
Nearby products and look-alikes can have different ingredients or hazards. Use the linked cluster pages to identify the closest exact match instead of treating every exposure as the same. Open a closely related item page →
FAQ
Your vet sets the dose, and it is specific to your dog's weight and condition. Nothing on this page is a dose to give. What matters after an accidental exposure is how much more than the prescribed amount was taken.
For a single extra dose of your dog's own prescription with no signs, call your vet's line for advice before deciding anything. Do not double up a later dose to compensate, and do not stop a prescribed course on your own.
Call if a whole container may have been emptied, if the amount is uncertain, if your dog is vomiting repeatedly or seems unsteady, or if this is a human product rather than your dog's prescription.
- Merck Veterinary Manual — poisonings from human prescription drugs
- ASPCA Animal Poison Control Center — medication hazards in pets
- Merck Veterinary Manual: Poisonings from human prescription drugs
- Pet Poison Helpline: Top 10 human medications poisonous to pets
- ASPCA Animal Poison Control