Elanco Announces FDA Approves Improved Zenrelia™ (ilunocitinib tablets) Label, Removing Vaccine-Induced Disease Language

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Sep 23, 2025, 06:27 ET

FDA now concludes "the totality of evidence supports removal of the risk of fatal vaccine-induced disease from modified live virus vaccines from the labeling"ⁱ
Further evaluation of supplemental scientific data drove this FDA update; data now peer-reviewed and published
Real-world success and experiences from dermatologists and general practice veterinarians around the U.S. and the world further demonstrate Zenrelia's efficacy

INDIANAPOLIS, Sept. 23, 2025 /PRNewswire/ -- Elanco Animal Health Incorporated (NYSE: ELAN) today announced important updates to the U.S. Zenrelia label, following the Food and Drug Administration (FDA) review of supplemental scientific data.

Approved by the FDA in September 2024, Zenrelia is an effective, convenient, and safe once-daily oral JAK inhibitor for control of itching and inflammation associated with skin allergies in dogs at least 12 months of age. Over half a million dogs around the world have been treated with Zenrelia. Elanco is inspired by the positive and growing feedback from dermatologists, general practice veterinarians and pet owners.

At launch, the U.S. Zenrelia label included language based on the outcome of a laboratory study of unvaccinated dogs dosed at three times the label dose of Zenrelia. During that study, an outbreak of concurrent diseases occurred, complicating interpretation of the results.ⁱⁱ

Upon evaluation of additionally submitted data, the FDA now concludes that "the totality of evidence supports removal of the risk of fatal vaccine-induced disease from modified live virus vaccines from the labeling,"ⁱ and this language has subsequently been removed from the Zenrelia label in the U.S. The label Boxed Warning continues to advise discontinuation of Zenrelia for at least 28 days to 3 months prior to vaccination and withholding Zenrelia for at least 28 days after vaccination due to the risk of inadequate immune response to vaccines.

"We appreciate the FDA's commitment to reviewing the latest submitted scientific data to ensure that the label is reflective of the totality of evidence," said Dr. Ellen DeBrabander, Executive Vice President, Research & Development at Elanco. "This now brings the U.S. label a step closer to the approved Zenrelia label in markets such as the European Union, Great Britain, Brazil and Japan. We are committed to generating additional data in our efforts to further strengthen the U.S. label."

Scientific Studies Support Safety and Efficacy of Zenrelia
The totality of the evidence around Zenrelia continues to support the safety and efficacy of the product when used according to label directions. Prior to using this drug, it is important to read the entire label, including the Boxed Warning related to concurrent vaccine administration. Veterinarians can review additional peer reviewed and published studies on Zenrelia.

Real-World Success
Zenrelia has achieved remarkable performance across the globe in its first year, with product now available in the European Union, Great Britain, Brazil, Canada, Japan, and the United States. Dogs like Trooper, Scrappy, Remi, Missy, Hunter and River have seen real-world outcomes from Zenrelia. Learn more about their stories here.

"Zenrelia has gained momentum, with more veterinarians buying and prescribing Zenrelia to more dogs each month," said Bobby Modi, Executive Vice President, U.S. Pet Health and Global Digital Transformation at Elanco. "More than 90% of U.S. veterinarians are aware of Zenrelia and 80% of U.S. clinics re-ordered Zenrelia after they experience results first-hand."

Earlier this year, Elanco released the America's Itchy Dogs Report. The first-of-its-kind report includes results from multiple surveys revealing just how badly dogs around the country are itching for relief. Nearly 8 in 10 itchy dog owners who have switched veterinarians report they switched after 3 visits or less.ⁱⁱⁱ This puts more pressure on dermatologists and veterinarians to help dogs find itch relief quickly.

"I've been using Zenrelia in my practice for several months," said Dr. Tannetje Crocker, owner of Alta Vista Animal Hospital in Fort Worth, TX. "With fall allergies in full-swing, I'm using Zenrelia as a first-line treatment option, both in new, as well as seasonal cases. This updated label makes it easier for me to have conversations with pet owners about Zenrelia."

When initiating treatment with Zenrelia, refer to label directions. Zenrelia should only be used in dogs that are up to date on vaccinations, at least 12 months old and free from serious infection.

"As a dermatologist, I tend to see patients that need quick improvement—the owner is likely frustrated, the dog is itchy and inflamed, and I know that I need to help them find relief," Dr. Andrew Rosenberg, veterinarian and President of the American College of Veterinary Dermatology (AVCD). "Zenrelia has become an integral component of my first-line therapeutic approach."

Learn more about Zenrelia at Zenrelia.com.

INDICATIONS
Zenrelia is a prescription medication used to control itching and inflammation associated with skin allergies for dogs over 12 months of age.

IMPORTANT SAFETY INFORMATION
Read the package insert, including the Boxed Warning, before using this drug. For full prescribing information speak with your veterinarian, call 1 888 545 5973 or visit www.elancolabels.com/us/zenrelia.

WARNING: INADEQUATE IMMUNE RESPONSE TO VACCINES. Based on results of the vaccine response study, dogs receiving Zenrelia are at risk of an inadequate immune response to vaccines. Discontinue Zenrelia for at least 28 days to 3 months prior to vaccination and withhold Zenrelia for at least 28 days after vaccination. Dogs should be up to date on vaccinations prior to starting Zenrelia. Do not use in dogs less than 12 months old or dogs with a serious infection. Dogs should be monitored for infections because Zenrelia may increase the chances of developing an infection. Neoplastic conditions (benign and malignant) were observed during clinical studies. The most common side effects were vomiting, diarrhea and tiredness. Zenrelia has not been tested in dogs used for breeding, pregnant, or lactating dogs and has not been evaluated in combination with glucocorticoids, cyclosporine, or other immune suppressive drugs.

ABOUT ELANCO
Elanco Animal Health Incorporated (NYSE: ELAN) is a global leader in animal health dedicated to innovating and delivering products and services to prevent and treat disease in farm animals and pets, creating value for farmers, pet owners, veterinarians, stakeholders and society as a whole. With 70 years of animal health heritage, we are committed to breaking boundaries and going beyond to help our customers improve the health of animals in their care, while also making a meaningful impact on our local and global communities. At Elanco, we are driven by our vision of Food and Companionship Enriching Life and our purpose – all to Go Beyond for Animals, Customers, Society and Our People. Learn more at www.elanco.com.

Investor Contact: Tiffany Kanaga (765) 740-0314 [email protected]
Media Contact: Season Solorio (765) 316-0233 [email protected]

ⁱ Supplemental FOI Summary
ⁱⁱFent, G.M., Despa, S., Gabor, L. et al. Response to primary canine core vaccination in 10-month-old seronegative dogs treated with three times the recommended therapeutic dose of Ilunocitinib tablets (Zenrelia™). BMC Vet Res 21, 461 (2025). https://doi.org/10.1186/s12917-025-04896-5ⁱⁱⁱ Elanco Animal Health. Data on File.

SOURCE Elanco Animal Health