Vetoquinol Viralys Powder Immune Supplement for Cats, 21.2-oz

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At a Glance

  • Immune Support
  • Eye Care
  • All Lifestages

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About This Item

Details

  • 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.
  • Manufactured according to rigorous pharmaceutical standards, L-Lysine powder can be safely administered with no known side effects for as long as required.

Ingredient Information

Instructions

FAQ

Learn More About Vetoquinol From Our Team of Experts

Vetoquinol Viralys

Viralys L-Lysine Supplement for Cats

Support your cat’s immune system with Viralys L-lysine supplement! The key ingredient, lysine, supports normal eye health, respiratory health, and helps your cat maintain a strong immune system

Viralys can help cats manage conditions responsive to lysine, including:

• Squinting, watery, red, and/or itchy eyes

• Sneezing

• Runny nose

• Congestion

For Cats and Kittens          

Viralys can be given to cats and kittens of any age to support a healthy immune system.

Maintain Eye Health Support

L-lysine helps support normal eye function and health in cats and kittens.

Respiratory Health

Viralys is formulated to support respiratory health in cats and kittens.

Easy to Give

Even picky cats love the tasty maple-flavored oral gel or fish and poultry-flavored powder!

Satisfaction Guarantee

The makers of Vetoquinol are so sure your pet will like their products that they come with a 100% satisfaction guarantee.

Also Try Enisyl-F!

From Vetoquinol, Enisyl-F L-lysine supplement helps support immune health in cats and kittens of all ages.

Cats love the tasty chicken liver flavor of the easy-to-give bites or the tuna-flavored oral paste - giving you more options for high-quality immune support.

About Vetoquinol

Vetoquinol believes that a healthy pet is a happy pet. That’s why they are committed to creating uniquely formulated products that are easy to administer and designed to foster good health at every life stage. Since 1933, this independent family business has been on a mission dedicated exclusively to animal health. Their goal every day is to enrich the lives of pet parents by helping their pets be well and thrive!

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Questions & Answers

33 Customer Questions

I only feed the neighborhood cats once daily, so can I double the dosage to do this?

Answer by Kymm • Dec 19, 2025
I only give this as a supplement to my cats once per day and it definitely has an impact. Their coats are shiny, their eyes are bright and they are very healthy.

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 Chewy • Jul 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.

Towards the end of the Viralys, there is tan/brown powder. Is this safe to use or should I throw it out?

Answer by Chewy • Aug 31, 2021
The tan or brown powder is flavoring. It tends to fall to the bottom of the tub over time. It's recommended to shake the tub before every use to keep it mixed.

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 Chewy • Jan 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.
Reviews
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4.7
Rated 4.7 out of 5 stars
1913 Ratings
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Customers Mention

Chewy identifies key considerations with the help of artificial intelligence and our veterinarians.

Effectiveness

90% Positive

Form and Administration

88% Positive

Ingredients

91% Positive

Nutritional Value

90% Positive

981 Customer Reviews

Rated 1 out of 5 stars
By Taylor on Feb 2, 2026

Upset tummy

Sadly this made my boy cry and throw up. We did one full day and a half day and on the second day he started crying and throwing up twice throughout the day after

Sadly this made my boy cry and throw up. We did one full day and a half day and on the second day he started crying and throwing up twice throughout the day after breakfast. He didn’t on the third day at all or sense I’ve stopped using this. He does have a sensitive stomach so I think maybe this was just a little too much for him.

Rated 4 out of 5 stars
By Katrina on Dec 28, 2025

Vet Recommended

This was recommended by my vet after a surprise visit due to my cat coming down with the Feline cold (sneezing, coughing, lethargic, etc). I was directed to administer

This was recommended by my vet after a surprise visit due to my cat coming down with the Feline cold (sneezing, coughing, lethargic, etc). I was directed to administer one scoop twice a day in her food. My cat eats wet food so this has been very easy, with no fuss from her. Chewy’s price is significantly cheaper than my vets pricing, which I truly appreciate. I would purchase this product from Chewy if needed agin. My cat has been on this supplement for over two weeks, going on three. Over this time, her symptoms have slowly subsided but have not completely gone away. I will continue the supplement, as they do provide relief, but may ask my vet for something different if her symptoms do not completely clear.

Rated 5 out of 5 stars
By Joyce on Jan 14, 2026

Works Great

It boosts the immune system to help fight against URI etc. It has worked with many of my cats that has slight symptoms - sneezing , runny nose , goopy eyes - just

It boosts the immune system to help fight against URI etc. It has worked with many of my cats that has slight symptoms - sneezing , runny nose , goopy eyes - just sprinkle the advised dosage into the their food . Within 24-48 hours a huge improvement . They like the taste so no problem getting them to eat it in their food. This will not stop URI that has already created issues - that needs vet care . Viralysis helps with prevention

Rated 5 out of 5 stars
By Robert on Dec 27, 2025

Feline AIDS help

I have three outside cats with feline AIDS. This product is great in easing the upper respiratory problems these cats suffer with. I use it every day on top of wet

I have three outside cats with feline AIDS. This product is great in easing the upper respiratory problems these cats suffer with. I use it every day on top of wet cat food. The cats still devour the wet food, but the medication helps cut down on breakouts of respiratory problems. The more it’s part of the daily regimen, they don’t have nearly the problems they have without it.

Rated 4 out of 5 stars
By Patti on Jan 28, 2026

My cats eats it.

I tried a chew supplement from my vet and a paste and my cat wouldn’t eat either. Viralys is a powder that mixes easily in wet food. My cat hasn’t missed a dose

I tried a chew supplement from my vet and a paste and my cat wouldn’t eat either. Viralys is a powder that mixes easily in wet food. My cat hasn’t missed a dose since I got it. It’s too early to tell if it helps with his condition.

Rated 5 out of 5 stars
By Melanie on Jan 27, 2026

Great immune help

My kitty was getting upper respiratory cold a couple times a year. He's an older kitty so his health is especially important to me. Since using Vetoquinol Viralys

My kitty was getting upper respiratory cold a couple times a year. He's an older kitty so his health is especially important to me. Since using Vetoquinol Viralys Powder he has been health and happy. No colds. Great product.

Rated 5 out of 5 stars
By Madeline on Jan 14, 2026

Life saver!

This product along with eye drops helped get rid of my cat’s eye irritation. I was given this years ago from a vet when our other cat had conjunctivitis, so I was

This product along with eye drops helped get rid of my cat’s eye irritation. I was given this years ago from a vet when our other cat had conjunctivitis, so I was very happy that I could buy this from Chewy without a trip to the vet. It came super fast!

Rated 3 out of 5 stars
By Kim on Dec 18, 2025

Cats notice I added this to their food

This is the 2nd item with Lysine I have tried for my cats because my vet recommended I add to my cats' diets. My cats normally eat most poultry type products, so

This is the 2nd item with Lysine I have tried for my cats because my vet recommended I add to my cats' diets. My cats normally eat most poultry type products, so I can only assume they are not liking the fish flavors in these products. I think I found one more product with Lysine that is chicken based that I may try before giving up. I was so wanting them to like this product.

Rated 5 out of 5 stars
By JC on Dec 23, 2025

Helpful preventative

As my cat has gotten older, she's gotten a few colds that lingered. My vet recommended giving her this twice a day to boost her immune system and prevent future

As my cat has gotten older, she's gotten a few colds that lingered. My vet recommended giving her this twice a day to boost her immune system and prevent future colds. She eats it easily mixed in her food (she loves most food so this is not normally an issue for her) and so far it has worked at preventing more colds.

Rated 5 out of 5 stars
By some on Feb 2, 2026

Vetoquinol

Kittens had dark eye boogers so vet suggested Lysine so I got this brand. I could hide it in their wet food and they ate it no problem. There eyes got better . I

Kittens had dark eye boogers so vet suggested Lysine so I got this brand. I could hide it in their wet food and they ate it no problem. There eyes got better . I would buy again