Vetoquinol Enisyl-F Lysine Bites Chicken & Liver Flavored Immune Supplement for Cats, 6.35-oz bag

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At a Glance

  • Immune Support
  • Eye Care
  • All Lifestages

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About This Item

Details

  • Made in the USA.
  • Comes in a highly palatable poultry flavor, and may also be used as directed for as long as needed.
  • These small, bite-sized treats are specifically developed for cats and kittens to help treat conditions responsive to lysine such as upper respiratory problems.
  • They also work to reduce the severity and duration of symptoms caused by the feline herpes virus.
  • Routine administration of these treats can reduce herpes flare-ups as well as inflammation of the eyes, conjunctivitis, squinting, sneezing, sinus congestion and more.

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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Frequently bought together

Questions & Answers

8 Customer Questions

Approximately how many chews are in a bag?

Answer by Sarah • Aug 11, 2025
According to the email Chewy sent me there are appx 360 chews per bag. With an adult cat dosing 24 chews/day that's a 15 day supply

Can the bites and the powder be used together? We've begun feeding wet food only once a day for weight management and our herpes-positive cat is now only getting one dose of Lysine.

Answer by Chewy • Jun 12, 2018
Before combining any supplements, vitamins, or medications, it's always recommended to consult your vet for the healthiest and most accurate use.

how big are the bites?

Answer by Chewy • Jan 09, 2019
The treats are approximately the size of a green pea.

Are these soft or crunchy?

Answer by Chewy • Mar 03, 2024
These have a hard, crunchy texture.
Reviews
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3.8
Rated 3.8 out of 5 stars
686 Ratings
Terms & Conditions

468 Customer Reviews

Rated 1 out of 5 stars
By Ericka on Jan 25, 2026

These "bites" really bite. Too hard to eat. Useless.

These things are rock hard. With an adult cat needing to eat 24 of them per day, there's no way this will work. I have tried cutting them with a very sharp knife

These things are rock hard. With an adult cat needing to eat 24 of them per day, there's no way this will work. I have tried cutting them with a very sharp knife and tried mashing them with a mortar & pestel, but nothing works. They are too darned hard. We have put them in a ziplock bag with a wet paper towel to try to get them to soften up (without making them slimy), and that really doesn't work. The cats WANT to eat them, but they're just too hard to chew, and the cats end up spitting them out. I will NOT buy these again. Too much money for something that can't ar unable to eat. The powder by the same brand seems to work much better. We'll stick with mixing that into the cat food. Also, the powder does not have a couple of concerning ingredients that the "bites" have (i.e., sugar and titanium dioxide). So I think these are just going in the trash. Throwing money away. <<sigh>>

Rated 1 out of 5 stars
By Deb on Jan 2, 2026

SMELLED BAD. MY CAT REFUSE TO TRY 1

The cat is purchased these for refused to eat one. He smelled it and walked away. The other 3 cats refused as well. I tried mixing them in wet food...and with 3

The cat is purchased these for refused to eat one. He smelled it and walked away. The other 3 cats refused as well. I tried mixing them in wet food...and with 3 real treats...nope. None of them will eat them most likely based on smell. A smaller bag, less expensive would have been nice to try.

Rated 1 out of 5 stars
By Kelly on Jan 25, 2026

Treats

My cat does not like them. I don't know what exactly it is. I don't know if it's the flavor he doesn't like or if maybe it's too hard but he does eat other crunchy

My cat does not like them. I don't know what exactly it is. I don't know if it's the flavor he doesn't like or if maybe it's too hard but he does eat other crunchy treats. I just don't know why he doesn't like these

Rated 1 out of 5 stars
By Ka on Jan 31, 2026

Size too large. Cat not interested.

Cats have small mouths. They need to make smaller bites. My cat sniffed and wasn’t even interested enough to try. If they were smaller I might be able to give them

Cats have small mouths. They need to make smaller bites. My cat sniffed and wasn’t even interested enough to try. If they were smaller I might be able to give them like a pill.

Rated 5 out of 5 stars
By Carol on Jan 22, 2026

Feline Herpes

This works very well to control my cat's feline herpes. She's a small adult so I give her 9 in each of 2 meals a day.

This works very well to control my cat's feline herpes. She's a small adult so I give her 9 in each of 2 meals a day.

Rated 5 out of 5 stars
By Linda on Jan 6, 2026

Our of this world

Comet ur cat loves his l-Lysine chew. He has no prpblem taking this in the evening. Thank you fir such a great product.

Comet ur cat loves his l-Lysine chew. He has no prpblem taking this in the evening. Thank you fir such a great product.

Rated 2 out of 5 stars
By Ciara on Oct 17, 2025

Treats are too hard

One of my cats really wanted these treats, the other didn’t care for it because the treats are too hard. The cat that liked the treats had a hard time chewing them

One of my cats really wanted these treats, the other didn’t care for it because the treats are too hard. The cat that liked the treats had a hard time chewing them too. Ended up switching to the powder instead

Rated 1 out of 5 stars
By Holly on Jan 25, 2026

These bites were very hard.

My elderly cat couldn’t eat these. They were too hard for her to chew.

My elderly cat couldn’t eat these. They were too hard for her to chew.

Rated 5 out of 5 stars
By Leah on Jan 30, 2026

Great product

My vet recommended this product for my cats eyes. It works great.

My vet recommended this product for my cats eyes. It works great.

Rated 4 out of 5 stars
By Brandy on Aug 25, 2025

Yummy alternative to the powdered lysine

This lysine treats seemed to be well liked by my 5 month old kitten. The only reason I give it 4 stars is that the treat is a little on the hard size and slightly

This lysine treats seemed to be well liked by my 5 month old kitten. The only reason I give it 4 stars is that the treat is a little on the hard size and slightly large for a kitten, but she manages fairly well to eat them and seems to enjoy the taste. I will continue to purchase these in the future as they seem to help support her immune system quite well.