Apoquel has very scary side effects. From the Apoquel package insert, approximately 6% of test dogs developed cancers.⁠ ⁠ Side effects listed when using Apoquel include vomiting, diarrhea, liver failure, overwhelming bacterial and fungal infections, including pneumonia. ⁠ ⁠ Apoquel does not "cure" anything; it is an immune suppressant. It is only labeled for use in dogs, and is unsafe for puppies under 12 months or senior dogs due to their weakened immune system. ⁠ ⁠ Allergies, skin infections,