The side effects of aspirin and ibuprofen are usually so minor in humans that they're hardly noticeable. In dogs, however, these same medications can have side effects so severe that they are life threatening.
Aspirin and Ibuprofen
Aspirin can upset your dog's stomach, stop blood from clotting properly and cause kidney failure. If it has an enteric coating, it may not dissolve in your dog's stomach the way it is supposed to, and this can lead to risk of overdose -- particularly if the dog ingested more than a couple, depending on size. Ibuprofen can cause the same problems as well as vomiting, seizures, diarrhea and even death. Because of these serious side effects, you should not give your dog aspirin or ibuprofen, unless under the direct guidance of your veterinarian.
Veterinary Use
Veterinarians do not typically prescribe aspirin or ibuprofen to dogs as a first choice, but when other drugs are not suitable they may turn to these medications "off-label" for pain relief. Both reduce swelling and pain but must be given in a correct dose to be effective without creating serious side effects. Your vet has answers.