Vetoquinol Viralys Powder Immune Supplement for Cats

By Vetoquinol
Rated 4.5911 out of 5 stars

Product Form:

Selected: Product Form:

Product Form:

Selected: Product Form:


Selected: Size:


Selected: Size:

$28.99Chewy Price
$27.54Autoship Price
Autoship (Save an extra 5%)
Save 35% (up to $20) on your first order and 5% on future orders. Choose Autoship in Checkout. Skip or cancel anytime.

Temporarily Out of Stock
Get notified when this item is back in stock.

Compare Similar Items

Customer Rating
Rated 4.2876 out of 5 stars
Rated 4.5053 out of 5 stars
Rated 3.9055 out of 5 stars
Rated 4.0078 out of 5 stars
Rated 3.8 out of 5 stars
$20.99Chewy Price
$17.99Chewy Price
$17.34Chewy Price
$24.99Chewy Price
$19.49Chewy Price
$19.94Chewy Price
$17.09Chewy Price
$16.47Chewy Price
$23.74Chewy Price
$18.52Chewy Price
Top IngredientsActive Ingredients: L-Lysine Hydrochloride., Inactive Ingredients: Citric Acid, Edetate Disodium...Active Ingredients: L-Lysinehydrochloride., Inactive Ingredients: Brewer's Dried Yeast, Hydrolyzed Fish (Enzymatic)...Active Ingredients: L-Lysine, N, N-Dimethylglycine HCl (D mg)....Dried Brewers Yeast (grain & soy free); Catnip (Leaf); Chicken Liver (hydrolysate); Fish Oil (Salmon); L-Lysine Mono HCl; Mixed Tocopherols or Natural Tocopherols (Natural Preservative); Quercetin Dihydrate; Rosemary Leaf Extract....Active Ingredients: L-Lysine Hydrochloride., Inactive Ingredients: Citric Acid, Edetate Disodium...
LifestageKitten, Adult, SeniorKitten, Adult, SeniorKitten, Adult, SeniorKitten, Adult, SeniorAdult
Health FeatureEye Care, Immune Support, Respiratory CareImmune SupportImmune SupportEye Care, Immune Support, Respiratory Care, Allergy ReliefImmune Support
Food FlavorMolassesChickenPoultry, Meat, Chicken, LiverChicken, Tuna
Food FormSupplementSupplementSupplementPowderSupplement
Special DietNo Corn No Wheat No Soy, Non-GMO, Natural

About This Item


  • A highly palatable L-Lysine HCI Nutritional oral powder for cats that may be sprinkled over dry food or mixed with a small amount of canned food
  • For cats and kittens as a nutritional supplement for conditions responsive to Lysine such as upper respiratory problems or feline herpes.
  • This powder will also help reduce inflammation of the eyes, conjunctivitis (eye discharge), squinting sneezing, sinus congestion, and so much more.
  • This L-Lysine supplement is specifically developed for cats and kittens and contains naturally occurring amino acids
  • Made in the USA and manufactured according to rigorous pharmaceutical standards, L-Lysine powder can be safely administered with no known side effects for as long as required

See More

Nutritional Information

Feeding Instructions


Play Video: Learn More About Vetoquinol From Our Team of Experts
Learn More About Vetoquinol From Our Team of Experts

Trusted Immune System Support

Adding L-lysine as a supplement to your cat's diet is an easy way to help support her long-term health. As a market leader with a wide range of L-lysine products, Vetoquinol puts this active ingredient in tasty chews and bite-size morsels, plus paste, gel and powder form so you can find the best way to offer it to your kitty. These supplements are specifically designed for felines to support the immune system, and maintain respiratory an

Seal of Quality

Out of thousands of animal supplement companies, only a hundred are audited NASC members, including Vetoquinol. That means they've undergone a comprehensive quality audit to earn the NASC Quality Seal. Displaying this seal on their products means that you can rest assured that they are committed to following the highest current standards of quality in the industry.

Enisyl-F & Viralys Products

Specially formulated Enisyl-F was the first lysine-based nutritional supplement developed for veterinary use for kitties. Supplementing with L-lysine is helpful for managing the symptoms of upper respiratory infections in kittens and cats that were strays, and those in shelters.


Veterinarian formulated to deliver just the right dose in a treat with cheese, chicken, liver and hickory smoke flavors.


Tiny mouthfuls of L-lysine disguised as a delicious snack with savory chicken fat and chicken liver.

Oral Paste

Highly palatable paste that can be given by mouth, mixed with food, or even applied to paws for your cat to lick off.

Oral Powder

Delivers L-lysine HCl in a powder with fish and poultry liver flavors that cats crave—just sprinkle it on top of food.

Oral Gel

Cats only need a small amount of this extremely palatable gel to get the benefits of L-lysine HCl.

About Vetoquinol

Vetoquinol is a family-owned company devoted exclusively to finding innovative solutions for animal health issues. They've shown more than 80 years of dedication, researching everything from oral hygiene to urinary and kidney health to create products that are effective and safe for the pets you love and care about. Founded in 1933 with an expertise in pet pain management and veterinary resources, Vetoquinol has gained the continued trust of pet parents and vets worldwide.
Shop Vetoquinol

Questions & Answers

31 Customer Questions

Is there any difference between L-Lysine and L-Lysine HCL. We have been giving our cat L-Lysince, but I see that Chewy only has L-Lysine HCL.
Answer by ChewyJul 29, 2018
The HCl denotes that the lysine is present as the hydrochloride salt. Salts changes the properties of the lysine, making it more soluble.

Does this supplement have chicken or fish in it?
Answer by ChewyJun 06, 2023
This supplement includes Hydrolyzed Fish (enzymatic) and Hydrolyzed Poultry Liver (enzymatic). For a complete list of ingredients, click the “Nutritional Info” tab, next to the “Description” tab, just under the product photos when viewed on a desktop. Click the "Nutritional Info" tab, next to the "Q&A" tab, towards the top bar above the product image when viewed on the app.

Can this product be mixed with their drinking water (kept in fridge) as some of my kids eat drive others eat wet. Thanks!
Answer by ChewySep 18, 2018
This supplement for cats may be sprinkled over dry food or mixed with a small amount of canned food.

What are the actual (beneficial) differences between Enisyl-F paste and Viralys gel or powder? I can't find dosing info for all 3 items to compare. Do they all provide 250 mg of Lysine HCL per serving?
Answer by ChewyJan 23, 2019
Enisyl-F Pump - 1ml contains 250mg. Viralys Gel - 1.25ml contains 250mg, Viralys Powder contains 500mg per scoop (0.52 grams). The lysine in either product is the same quality.

ReviewsWrite a Review

Rated 4.5911 out of 5 stars
582 Ratings
Would recommend to a friend

580 Customer Reviews

Rated 5 out of 5 stars
By kat on Sep 10, 2023

Helps cats with allergies

My beautiful cat, Atlas, developed allergies from god knows who, but her eyes would get very watery and she’d sneeze a lot. At first I wasn’t sure what was going on so I asked her doctor and she recommended buying this powder to help with her reactions. With a combination of allergy pills (Zyrtec), her eye cream (help with mucus build up), and this supplement, I was able to get her symptoms more controlled and now she’s better than ever :) her seasonal allergies haven’t came back since I started giving this to her last year! Now this isn’t to say they won’t come back, but as of now she’s in great health!! Hope this helps!

Rated 5 out of 5 stars
By Kiteeee on Sep 4, 2023

This Stuff Works Best

I'm glad I tried this stuff. My 12 yr old orange boy's allergies are bad. And he takea the lysine in treat form (broken into his food) or I i.pose the paste on his mouth, but this stuff avoids all that negotiation! I put it in his food and no problemo! One 500mg serving is so scant. He doesn't blink a cat's eye..we even put it in his crunches, which we add a little water or bone broth to. He doesn't tur. His nose up and it's working beautifully on his allergies! This ans 1/2 a Claritin that my Vet suggested. His respiratory issues, sneezing and overcrowding are gone! Yaaay! This tub should last since each 500mg scoop is so teeny! He gets 2 a day with meals.

Rated 4 out of 5 stars
By Catwrangler on Aug 8, 2023

Good so far

Been struggling to get senior kitty to reliably consume a lysine supplement. She’s quite finicky these days. Tried gel and chews over the years and now this powder. We use an immersion blender to turn pate canned food into the consistency of a creamy treat. Stir in this powder and she cleans her plate. *** this powder smells how I’d imagine a fish bum would smell. But the cat likes it so whatever. Breathe through your mouth when you open the container.

Rated 5 out of 5 stars
By Nic on Jul 26, 2023

Great to keep immunity strong

Between my roommates and I we have five orange cats. The two older boys came from a shelter down South and one of them has herpes outbreaks that affect his eyes. The three kittens (about 9 months right now) came from a hoarders home and one of them has a mystery problem causing high white blood cell count (not caused by bacteria, FIV, herpes or FeLV) and my kitten has weird eye issues where she has red crusty eye boogers. This stuff has been helping with keeping all their problems at bay. I use this brand because it mixes the best in food without clumping up from the liquid.

Rated 3 out of 5 stars
By Christine on Sep 25, 2023

It worked but at a cost

I can't say for certain (but giving this was the only variable) this caused kidney stones in my cat. It helped with keeping her immunity up but it wasn't worth the stones.

Rated 5 out of 5 stars
By Angel on Jul 23, 2023

it works!

I adopted a cat a couple years ago that had chronic respiratory infections (kitty herpes from the shelter). I couldn’t see giving him medications his whole life, so I did some research for something more natural and have bought this several times… I just sprinkle it on his food. I couldn’t believe how good it has worked! I never wrote a review for it before, but years later, it still keeps my kitty healthy!

Rated 2 out of 5 stars
By Lisa on Jul 10, 2023

Not suitable for chicken allergy

My cat is allergic to chicken and I read that this supplement would be OK because it supposedly only contains hydrolyzed chicken products. But after about a week of using it, he has broken out in his skin sores that he gets only from eating chicken products. So if your pet is allergic to chicken you probably don’t want to use this.

Rated 5 out of 5 stars
By Mike on Aug 2, 2023

Really Works & Worth The Price1

Our cat has sneezing fits and patchy hair loss. Vet recommended Viralys. We sprinkle a little over her crunchy food and she is symptom free. She seems to like or doesn't mind the taste. Better than trying to give a pill.

Rated 5 out of 5 stars
By Nelia on Jun 15, 2023


I have five medical and behavioral unadoptable rescue felines. One came in with Calisci virus that we did not catch. So, now all five suffer through breakouts. Viralys FAR extends the time between breakouts to almost none for a couple of them. I mix it in their wet food mornings and evenings and they LOVE it!

Rated 5 out of 5 stars
By Aly on Aug 2, 2023

Gave this to my 2 kittens under 16wks and they didn’t even notice it was in their food and their URI signs are gone