Aspirin for Dogs: Uses, Dosage, and Side Effects

PetMD’s medications content was written and reviewed by veterinary professionals to answer your most common questions about how medications function, their side effects, and what species they are prescribed for. This content shouldn’t take the place of advice by your vet.  

What Is Aspirin Used for in Dogs?

Aspirin​ (acetylsalicylic acid)​ is a human pain reliever that is ​​not recommended for dogs because it can cause serious side effects. Dogs process aspirin differently​ than people​, which increases the risk of stomach irritation and internal bleeding.

​​In rare, veterinarian-directed cases, aspirin may be used for a specific medical reason, such as to reduce ​blood clotting​​, but it​​​’​s generally not used anymore ​​because ​​safer​​, dog-specific​​ medication​​s—​​such as​​ ​​clopidogrel (Plavix)​​ ​​or veterinary-approved NSAIDs—are​​ available​. ​​​ 

If your dog is in pain, do not give aspirin​, but instead call your vet right away. ​​They​​ will recommend ​​safe​​ and appropriate treatment options.​​

Baby Aspirin for Dogs 

Baby aspirin (low-dose aspirin) should never be given to dogs without a veterinarian’s specific guidance. Even at lower doses, baby aspirin can cause stomach irritation, ulcers, and bleeding in dogs. 

Because dogs process aspirin differently than people, baby aspirin is not inherently safer. If your dog is in pain, contact your veterinarian to discuss safer, dog-specific treatment options. 

Is Aspirin FDA-Approved for Dogs? 

No, aspirin is not FDA-approved for use in dogs, although pet-labeled products are available. It is, however, FDA-approved for human use.      

Veterinarians can legally prescribe certain human drugs for use in animals in certain circumstances. This is called extra-label or off-label use because this use is not described on the drug label. 

Speak with your veterinarian about whether aspirin is right for your dog.    

How Does Aspirin Work in Dogs?

Aspirin works by reducing substances in the body that cause pain, inflammation, fever, and blood clotting.  

In dogs, aspirin has been used primarily for its anti-clotting effects rather than for pain relief. However, it’s rarely used today by veterinarians because safer, dog-specific medications are available.          ​     ​​​     ​​​     ​​​     ​​ 

Aspirin also ​​​blocks helpful protective substances in the stomach and kidneys​​. This can increase the risk of stomach ulcers, gastrointestinal bleeding, and kidney injury. For these reasons, aspirin is generally not recommended for pain control in dogs.​ 

How To Give Aspirin to Dogs

Do not give aspirin to your dog—including any formulations of aspirin that contain acetaminophen (Tylenol)— unless directed by your veterinarian.       

• ​​Your veterinarian will recommend an appropriate formulation of aspirin. ​​​​​     ​​​     ​​​     ​​ 

• Your veterinarian may recommend that you give aspirin with a meal to help reduce the chance of digestive upset.   

• Contact your veterinarian right away if your dog is experiencing any side effects (see below) after taking aspirin. ​     ​ 

​​​​​​​​​What Are the Side Effects of Aspirin in Dogs?

​​​Aspirin can cause serious side effects in dogs, especially affecting the gastrointestinal tract and kidneys. One of the most significant risks is the development of stomach or intestinal ulcers, which can lead to internal bleeding.​​ 

​​Black, tar-like stools may indicate gastrointestinal bleeding and require immediate veterinary attention. ​ 

Contact your veterinarian right away if you see any of ​the following ​signs:  

• ​​Decreased appetite​  

• Decreased energy level (​lethargy​)  

• ​​Vomiting​  

• Bloody vomit (can appear bright​-​red, or dark and look like coffee grounds)  

• ​​Diarrhea​  

• ​​Blood in the feces​ (can appear bright​-​red, or dark and tar-like)  

• ​​Nausea​  

• Abnormal bleeding or bruising   

Human Side Effects 

​​Due to possible side effects, humans should never use medicine dispensed for their pets and pets should not be given any medicine dispensed for a human’s use. ​ 

If you accidentally ingest a pet medication, seek medical attention in person or call Poison Control at 800-222-1222. 

When To Call Your Vet 

Call your veterinarian if you see any of the following, or if you have additional questions or concerns about the use of aspirin: 

• Severe side effects (above) 

• Your pet’s condition worsens or does not improve with treatment 

• You see or suspect an overdose 

What Happens if a Dog Overdoses on Aspirin?

Overdosages of aspirin (also known as aspirin poisoning) can be very serious. It can occur when a ​dog ingests ​​aspirin ​or when a​ pet parent ​accidentally gives too much of it.  

To avoid giving an unintentional overdose, do not give aspirin to your ​dog​ unless directed by a veterinarian. Some websites provide inaccurate dosing information that could result in an overdose. 

Signs of an overdose include:  

• ​​Rapid breathing or panting​ 

• Decreased activity (lethargy) 

• Loss of appetite 

• Vomiting (which may contain bright-red blood or digested blood that looks like coffee grounds) 

• Diarrhea 

• Dark, tar-like stools 

• Elevated body temperature 

• Weakness 

• ​​Incoordination​ 

• ​​Seizures​ 

• ​​Coma​ 

• Death 

If you suspect an overdose, immediately seek emergency veterinary care or contact an animal poison control center. Consultation fees often apply. 

• Pet Poison Helpline 855-764-7661  

• ASPCA Animal Poison Control 888-426-4435  

How To Store Aspirin for Dogs

Keep the following storage tips in mind for this medication: 

• Keep​ the​ container tightly closed and away from moisture and light.  

• Keep out of reach of children and pets.