The label says, word for word:
This product has been shown to be effective for the treatment of dogs against allergic dermatitis and atopic dermatitis.
This product has not been tested in pregnant, lactating or breeding animals.
This product is intended for subcutaneous use only.
Do not mix with other products.
In case of human exposure, contact a physician.
Every approved medicine has a field study behind it, and the label prints what happened:
Based on voluntary post-approval global adverse product experience reporting, the following adverse events have been observed in rare cases (more than 1 but less than 10 animals in 10,000 dogs treated): Hypersensitivity reactions (anaphylaxis, facial edema, urticaria). In such cases, appropriate treatment should be administered immediately.
USDA-licensed veterinary biologic, not an FDA-approved drug: the package insert carries a USDA Veterinary License Number ("VLN 190/PCN 9580.03") and describes the product as "Canine Allergic Dermatitis Immunotherapeutic For Use in Dogs Only" and "a ready-to-use, sterile liquid containing a caninized monoclonal antibody (mAb) against interleukin-31 (IL-31)." There is no DailyMed label (DailyMed search for "cytopoint" returns "No Drug Package Labels found"), so the manufacturer's own package insert was used for all quotes.
The emergency page sorts the signs by how long you have, and the symptom checker asks what you are seeing. Reactions to a medicine can also be reported to the FDA yourself: how to report a problem.