Medically Reviewed By: Medsdog Team
Last Updated: August 2026
CAUTION: “Based on results of the vaccine response study, canines 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.”
Benign and malignant developments (including cancer) and infections were also noted in some of the dogs treated with Zenrelia during clinical studies. If your dog displays unusual symptoms, deteriorating symptoms or side effects that don’t improve, seek veterinary advice quickly to assess and manage.
The Zenrelia (ilunocitinib tablets) dosage for dogs is 0.6–0.8 mg/kg (0.27-0.36 mg/lbs), given as one tablet dose by mouth, once daily. Zenrelia is only approved for dogs 12 months or older weighing at least 6.6 lbs (3.0 kg).
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Zenrelia® Dosage Calculator For Dogs
Accurate Once-Daily Ilunocitinib Dosing for Dogs (12 Months or Older)
Minimum weight requirement for Zenrelia treatment is 6.6 lbs (3.0 kg).
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Disclaimer: This guide is for informational purposes only and is not a substitute for professional veterinary advice. This guide only alllies to the Zenrelia tablets for dogs.
Key Takeaways
- The Zenrelia dose chart is weight-based: 0.6–0.8 mg/kg (0.27–0.36 mg/lb) of ilunocitinib, once daily.
- Zenrelia (ilunocitinib) is FDA-approved (NADA #141-585, approved September 2024) to control pruritus from allergic dermatitis and manage atopic dermatitis in dogs.
- Minimum requirements: 12 months of age and 6.6 lbs (3.0 kg) body weight.
- Can be given with or without food, once a day, long-term if your vet recommends it.
- Carries an FDA Boxed Warning about vaccine timing — see below before you start treatment.
- Most common side effects are vomiting, diarrhea, and lethargy.
What Is Zenrelia For Dogs?
Zenrelia® (ilunocitinib tablets) is a prescription medicine for dogs which has been approved by FDA to help control pruritus (itching) associated with allergic dermatitis and manage signs of atopic dermatitis. Zenrelia dosage for dogs is a Janus kinase (JAK) inhibitor and contains the drug ilunocitinib, which is an immune-modulating drug that helps to diminish the inflammatory response that causes itchy, irritated skin.
Zenrelia is for use in dogs 12 months or older and is dosed by body weight at 0.6 – 0.8 mg/kg as an oral tablet once per day. Reduces overgrooming, scratching, chewing and biting, which is associated with allergic skin disease and causes discomfort in your dog and helps prevent hair loss and complications like secondary skin infections that can occur from excessive scratching.
Zenrelia is a prescription only medicine, and as such, should only be used under veterinary supervision.
Common uses of Zenrelia in dogs are:
- Allergic atopic dermatitis from environmental allergens like pollen, dust, mold and grass.
- A type of allergic dermatitis causing chronic itching and inflammation of the skin.
- Ectoparasite hypersensitivity such as flea allergy dermatitis.
- Dermatitis, an allergic reaction to certain protein in the food eaten.
- Contact dermatitis from direct contact with irritants such as plants, chemicals, or fabrics.
Your vet can decide if Zenrelia is an appropriate treatment depending on your dog’s particular allergy and skin problem; the product can be used for dogs over 12 months of age and is approved by the FD
Zenrelia Dosage for Dogs Guidelines
Zenrelia (ilunocitinib tablets) are approved for dogs 12 months of age or older and at least 6.6 lbs (3.0 kg). Some studied regarding ilunocitinib tablets shows that canines receiving Zenrelia are at risk of an inadequate immune response to vaccines. So it is suggeste to Discontinue Zenrelia for at least 28 days to 3 months prior to vaccination and withhold Zenrelia for at least 28 days after vaccination.
How much Zenrelia for dogs? For control of pruritus associated with allergic dermatitis in canines and control of atopic dermatitis the suggested Zenrelia (ilunocitinib tablets) dosage for dogs is 0.6–0.8 mg/kg (0.27-0.36 mg/lbs), given as one tablet dose by mouth, once daily.
It’s given orally, once a day, with or without food, and there’s no need to load or taper the dose it can be started and stopped as needed under veterinary guidance, since it clears from a dog’s system in about 24 hours.
Zenrelia Dosage Chart For Dogs By Weight 4.8mg, 6.4mg, 8.5mg, 15mg
| Dog Weight in Pounds (lbs) | Dog Weight in Kilograms (kg) | Recommended Tablet Administration Plan (Once Daily) |
| 6.6 to 8.8 lbs | 3.0 to 4.0 kg | Give half (0.5) of a 4.8 mg tablet |
| 9.0 to 11.7 lbs | 4.1 to 5.3 kg | Give half (0.5) of a 6.4 mg tablet |
| 11.9 to 14.3 lbs | 5.4 to 6.5 kg | Give half (0.5) of a 8.5 mg tablet |
| 14.6 to 17.6 lbs | 6.6 to 8.0 kg | Give one (1) 4.8 mg tablet |
| 17.9 to 23.4 lbs | 8.1 to 10.6 kg | Give one (1) 6.4 mg tablet |
| 23.6 to 31.1 lbs | 10.7 to 14.1 kg | Give one (1) 8.5 mg tablet |
| 31.3 to 35.3 lbs | 14.2 to 16.0 kg | Give one and a half (1.5) 6.4 mg tablets |
| 35.5 to 43.0 lbs | 16.1 to 19.5 kg | Give one and a half (1.5) 8.5 mg tablets |
| 43.2 to 54.9 lbs | 19.6 to 24.9 kg | Give one (1) 15 mg tablet |
| 55.1 to 62.4 lbs | 25.0 to 28.3 kg | Give two (2) 8.5 mg tablets |
| 62.6 to 82.5 lbs | 28.4 to 37.4 kg | Give one and a half (1.5) 15 mg tablets |
| 82.7 to 110.0 lbs | 37.5 to 49.9 kg | Give two (2) 15 mg tablets |
| 110.2 to 137.6 lbs | 50.0 to 62.4 kg | Give two and a half (2.5) 15 mg tablets |
| 137.8 to 165.1 lbs | 62.5 to 74.9 kg | Give three (3) 15 mg tablets |
Safety Notice: For giant breed dogs weighing 165.3 lbs (75.0 kg) or more, veterinarians should use a calculated combination of tablet strengths to safely stay within the targeted 0.6–0.8 mg/kg range.
Benefits of Zenrelia for Dogs
Zenrelia® provides effective relief for dogs with skin conditions associated with allergy by reducing itching and inflammation associated with allergic dermatitis and helps to control the signs of atopic dermatitis.
It contains the active ingredient, ilunocitinib, which helps reduce inflammation and the inflammatory pathways that cause allergic itch, helping dogs feel more comfortable and preventing excessive scrching that could lead to a greater amount of skin damage.
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Zenrelia’s Key Benefits
- Gives good relief of itching from allergic dermatitis.
- Helps control the signs of atopic dermatitis.
- Helps to decrease inflammation related to allergic skin disorders.
- Composed of the active ingredient, ilunocitinib, that acts on the immune response that causes itching.
- Delivered in a once-daily, hypoallergenic, unflavored oral tablet for easy administration.
- Is administered with or without food which makes it easier to take the medication daily at home.
Zenrelia drug for dogs is usually tolerated well but some dogs may vomit, have diarrhea or be lethargic (tired). Veterinarians will always give their recommendations and the product label will contain information about its safety and usage.
Possible Side Effects of Zenrelia in Dogs
As with any prescription drug, Zenrelia® may have side effects in some dogs. Most effects are only mild and short lasting, but more severe side effects have been seen in clinical studies. Please always follow your veterinarian’s advice and talk to your veterinarian if your dog shows persistent or severe symptoms while under Zenrelia.
Common Side Effects
- Vomiting
- Diarrhea
- Nausea
- Decreased appetite
- Lack of energy (lethargy or tiredness)
Less Common Side Effects
- Eye discharge
- Urinary tract infection (UTI)
- Low level of white blood cells
- Cough, wheeze, upper respiratory infection, or trouble breathing.
- Sneezing
- High levels of liver enzymes
- Bacterial skin infection
- Ear infection (otitis externa)
- Weight gain
- Increased thirst
| Side Effect | Zenrelia Group | Placebo Group |
|---|---|---|
| Vomiting or nausea | 22.1% | 16.1% |
| Diarrhea | 19.9% | 10.3% |
| Lethargy | 12.2% | 10.3% |
| Decreased appetite (anorexia) | 9.4% | 8.0% |
| Elevated liver enzymes | 5.5% | 2.3% |
| Urinary tract infection | 5.5% | 2.3% |
| Low white blood cell count (leukopenia) | 4.9% | 1.1% |
| Weight gain | 3.9% | 0% |
Less common effects reported across the Zenrelia clinical program include eye discharge, sneezing, coughing or wheezing, bacterial skin infection, ear infection, and increased thirst. Elevated liver enzymes were monitored closely in trials.
If your puppy needs extra liver support during treatment, ask your vet whether a milk thistle dosage for dogs supplement is appropriate alongside Zenrelia.
Benign and malignant growths (including one case of hemangiosarcoma) and opportunistic infections were also observed in a small number of dogs during clinical studies.
Because Zenrelia modulates the immune system, any new or worsening symptoms especially signs of infection should be reported to your vet promptly.
Do not combine Zenrelia with glucocorticoids (steroids) or cyclosporine unless specifically directed by your vet this combination has not been evaluated for safety. If your dog is currently on a steroid taper such as prednisone, talk to your vet before starting Zenrelia.
Zenrelia Overdose Concerns in Dogs
Excessive dosing of Zenrelia® can lead to more serious side effects and the severity of the effects will depend on the amount of the drug administered in comparison to the size of the dog and the length of time of the overdose. Overdose symptoms can include heightened effects of the medication’s common side effects, or more serious health problems with repeated overdoses or a large overdose.
Signs of a Zenrelia Overdose
- Heavy vomiting or diarrhoea
- Lethargy (low energy)
- Loss of appetite
- Symptoms of infection as a result of the immune suppression
- Deep infections between the toes (interdigital dermatitis) and swollen paws.
- Enlarged lymph nodes
- Between toes papilloma growths
- Low red blood cell count, low hematocrit (HCT), and low hemoglobin (Hgb)
- Depressed immune system
- Pneumonia
- Opportunistic infections are more likely to occur.
If you think your dog may have taken too much Zenrelia, be sure to contact your veterinarian or animal poison control center right away. Early veterinary attention is key to minimising risks of complications. Carry the medication container or prescription information if possible to help your veterinarian calculate the amount of medication your dog ingested and to treat your dog accordingly.
Zenrelia vs. Apoquel: How the Dosing Differs
Zenrelia and Apoquel (oclacitinib) are both JAK inhibitors used for the same conditions, but their dosing schedules and drug selectivity are different.
| Zenrelia (ilunocitinib) | Apoquel (oclacitinib) | |
|---|---|---|
| Dosing frequency | Once daily, from day one | Twice daily for 14 days, then once daily |
| Dose | 0.6–0.8 mg/kg | 0.4–0.6 mg/kg |
| Main JAK targets | JAK1, JAK2, TYK2 | JAK1, JAK3 |
| Rebound itch risk | Not typically seen (continuous once-daily dosing) | Possible when dropping from twice- to once-daily |
| FDA approval | September 2024 | 2013 |
In a head-to-head clinical trial research of 338 client-owned dogs, once-daily Zenrelia showed similar efficacy to Apoquel’s twice-then-once-daily schedule by Day 28, with a similar rate of adverse events between the two groups.
If your furry friend is currently on Apoquel and your vet is considering a switch, you can compare full dosing details in our oclacitinib dosage for dogs chart no washout period is typically needed between the two drugs, since both clear from the body within a similar short timeframe.
Which Canine Should Not Take Zenrelia
- Dogs under 12 months of age
- Dogs weighing less than 6.6 lbs (3.0 kg)
- Dogs with a serious active infection
- Dogs that are pregnant, lactating, or intended for breeding (safety not evaluated)
- Dogs due for vaccination within the required washout window (see Boxed Warning above)
- Dogs on glucocorticoids, cyclosporine, or other systemic immunosuppressants (safety not evaluated in combination)
Storage & How Supplied
Store Zenrelia tablets at room temperature, 59–77°F (15–25°C); brief excursions to 41–104°F (5–40°C) are acceptable. Keep tablets in the original container, in a dry place, out of reach of children and pets. Zenrelia is available in 4.8 mg, 6.4 mg, 8.5 mg, and 15 mg strengths, in 30-count blister packs and 90-count bottles.
FAQs
How to Store Zenrelia dose for Dogs
Keep Zenrelia at room temperature (15-25°C or 59-77°F). Short-term temperature changes from 41°F (5°C) to 104°F (40°C) are acceptable. Store in its original container until it is time to use it and in a dry place at room temperature that is not too hot or humid. Always keep Zenrelia out of reach of children and pets.
Is Zenrelia Dosage Safe For Dogs?
Yes. When used as directed by your veterinarian, Zenrelia is safe for healthy dogs 12 months or older and current on their vaccinations. It is contraindicated in the dog suffering from severe infections.
How soon will Zenrelia begin to work?
Zenrelia starts to work soon after it is taken as it is rapidly absorbed after oral administration. The onset of itch relief, however, may take some time (varying from dog to dog).
Can Zenrelia be used long term?
Yes. Zenrelia may be used to treat chronic conditions like atopic dermatitis for a long time. If your veterinarian prescribes the use of the medication when it is appropriate, there is no limit as to how long the medication can be used.
Is Zenrelia good for dog food allergies?
Yes. Zenrelia is labeled for the control of itching as a result of allergic dermatitis, including food allergy dermatitis. Clinical trials to obtain FDA approval included dogs with food allergies.
Does Zenrelia work like Apoquel?
Yes. Both Zenrelia and Apoquel belong to the class of drugs known as Janus kinase (JAK) inhibitors; they have different active ingredients. Zenrelia is administered once a day; Apoquel is usually administered twice a day for the first 14 days, and then once a day to maintain. Some dogs may respond better to either of the medications.
What’s Zenrelia made of?
Zenrelia is a synthetic Janus kinase (JAK) inhibitor called ilunocitinib that blocks an immune reaction that is part of the allergy reaction that causes itching. It is not a cortisone or antihistamine.
May I vaccinate my dog during its use of Zenrelia?
No. Vaccination should not generally be administered while your dog is on Zenrelia as the drug weakens the dog’s immune system, and may make the vaccine less effective or make your dog more susceptible to vaccine reactions. When therapy is discontinued, resume vaccination based on veterinarian’s recommendations.
Final Thoughts
Zenrelia® is a convenient once-daily prescription drug that helps control itching associated with allergic dermatitis and to manage atopic dermatitis in dogs 12 months of age and older. When prescribed and administered correctly by your veterinarian, it can help alleviate your dog’s allergy symptoms, making him more comfortable and happier.
Each dog is unique in how they react to treatment, so it is essential that the proper dosage be followed, side effects be monitored and veterinary check-ups take place during therapy sessions.
Contact your veterinarian before beginning or altering treatment if you have any questions regarding the proper Zenrelia dosage for dogs, any possible drug interactions or if it is not suitable for your dog. The safest and most effective use of Zenrelia is to make sure it is dosed properly and given under constant veterinary supervision.
