Also sold as Imuran, Azasan
This drug does have veterinary uses, but the product and the amount have to be chosen by a vet who knows your dog. There is no at-home dose.
Azathioprine is prescribed to dogs as an immunosuppressant, so a dog on it is under veterinary care. The concern after an excessive amount is the bone marrow, and that damage shows up days later rather than immediately.
Call a vet or poison control now. Do not wait for symptoms.
ASPCA Animal Poison Control (888) 426-4435 or Pet Poison Helpline (855) 764-7661. A consultation fee may apply.
Source-backed guidance. Not individualized veterinary advice.(more)
Compiled from veterinary poison-control and medical references, including the ASPCA Animal Poison Control Center, Pet Poison Helpline, and Merck Veterinary Manual.
Part of Steroids, immunosuppressants and skin treatments on our medication safety hub.
Do not wait for symptoms and do not wait until you have filled in the form below. Call first, then use the checklist while you are on the phone.
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 Azathioprine (Imuran) is dangerous
Azathioprine suppresses the immune system by interfering with the production of the building blocks cells need to divide, which is why vets use it in immune-mediated disease in dogs. Too much suppresses the bone marrow, so white cells and platelets fall, leaving the dog exposed to infection and bleeding. That drop takes days to appear, which means the important consequence of an overdose is invisible at the time of the call. It can also inflame the liver and the pancreas. Cats are far more sensitive than dogs and it is generally avoided in them.
Signs to watch for
Sedation, wobbliness, weakness, vomiting, slowed or labored breathing, or a heart rate that seems unusually fast or slow
Related items
Check the exact item or ingredient before assuming two similar exposures carry the same risk.
What to do next
Move the container out of reach, count what is missing, note the strength and the time, and call with the packet in front of you.
🚨Step-by-step: what to do in the first 10 minutes →Available 24/7. A consultation fee may apply.
A closer look at azathioprine (imuran)
Azathioprine suppresses the immune system by interfering with the production of the building blocks cells need to divide, which is why vets use it in immune-mediated disease in dogs. Too much suppresses the bone marrow, so white cells and platelets fall, leaving the dog exposed to infection and bleeding. That drop takes days to appear, which means the important consequence of an overdose is invisible at the time of the call. It can also inflame the liver and the pancreas. Cats are far more sensitive than dogs and it is generally avoided in them. The details below use the specific facts for this exposure, rather than treating it like every other medication question.
1. Start with the exact exposure
For a closely related comparison, read Prednisone (Prednisolone). There is no at-home dose for this drug, including where a vet has prescribed it before. The right amount depends on your dog's weight, the exact product, and what else your dog takes, and it has to be set by a vet who knows the case.
2. Use the facts to decide whether to monitor or call
Another helpful reference is Dexamethasone. Prevent any further access and call for advice. Do not give a dose of your own, and do not induce vomiting unless a veterinary professional directs you to. Call for any exposure that was not the dose your vet set, for a chewed container, or for sedation, weakness, unsteadiness, vomiting, or changes in breathing or heart rate.
3. If the details are uncertain
Follow the first 10 minutes guide. Move the container out of reach, count what is missing, note the strength and the time, and call with the packet in front of you.
FAQ
There is no at-home dose for this drug, including where a vet has prescribed it before. The right amount depends on your dog's weight, the exact product, and what else your dog takes, and it has to be set by a vet who knows the case.
Prevent any further access and call for advice. Do not give a dose of your own, and do not induce vomiting unless a veterinary professional directs you to.
Call for any exposure that was not the dose your vet set, for a chewed container, or for sedation, weakness, unsteadiness, vomiting, or changes in breathing or heart rate.
- Merck Veterinary Manual — poisonings from human prescription and over-the-counter drugs
- ASPCA Animal Poison Control Center — human medications
- FDA Center for Veterinary Medicine — extra-label drug use in animals
- Merck Veterinary Manual: Poisonings from human prescription drugs
- ASPCA Animal Poison Control
- FDA: The ins and outs of extra-label drug use in animals