Felisyl L-Lysine Granules Immune System Support, Salmon Flavor for Cats, 3.5-oz jar

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At a Glance

  • Immune Support
  • All Lifestages
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About This Item

Details

  • Adds much-needed nutrients and amino acids to your cat’s daily diet, providing nutritional support for a healthy, active cat with a strong immune system.
  • Contains L-lysine, an essential amino acid that supports normal immune system function, healthy tissue maintenance, and respiratory health.
  • Great for cats at any age, Felisyl can help your cat stay active by supporting their eye health and a normal inflammatory response.
  • Features an NASC Quality Seal, ensuring quality and safety standards pet parents can count on.
  • Founded by a veterinarian in 2000, Pet Health Solutions has a wide variety of veterinary strength supplements, medicated shampoos, and topicals for dogs, cats, and horses.

Ingredient Information

Instructions

FAQ

Learn More About Felisyl From Our Team of Experts

Felisyl L-Lysine Immune System Support

Breathe easy knowing your cat's respiratory system is supported for optimal wellbeing with Felisyl. Known for its immune-boosting properties, L-lysine helps strengthen your cat's natural defense mechanisms against common illnesses and infections.

Symptom Management

L-lysine is frequently used to manage symptoms associated with feline herpesvirus type-1 (FHV-1), a common viral infection in cats. Symptoms of FHV-1 include sneezing, eye discharge, and respiratory issues.

Tasty and Convenient

Felisyl L-lysine is easy to administer. It comes in granules, gel, and tasty soft chew form, making it hassle-free to incorporate into your cat’s daily routine. Your kitty will enjoy the delicious taste, too!

Supports Eye and Respiratory Health

Felisyl L-lysine can help reduce the severity, duration, and frequency of flare-ups of respiratory symptoms associated with viral infections, such as sneezing, coughing, and congestion.

About Pet Health Solutions

Pet Health Solutions is built on a philosophy of holistic pet care and wellbeing. With veterinarians on staff, their optimized formulations of supplements, topical, and dental products meet strict NASC (National Animal Supplement Council) standards.

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Frequently bought together

Questions & Answers

2 Customer Questions

What is the FULL ingredients list for this product? I want to know what all the fillers are...maltodextrin, magnesium oxide, etc?

Answer by Chewy • Apr 22, 2019
The full ingredients list for this product are as follows: L-Lysine, Natural Chicken Liver Flavor, Oat Flour, Rye Four, Soy Lecithin, Brewers Dried Yeast, Water, Arabic Gum, Glycerin, Canola Oil, Maltodextrin, Sodium Alginate, Calcium Sulfate, Citrus Pectin, Oat Meal, Sorbic Acid (preservative), Propionic Acid (preservative), and Mixed Tocopherols (preservative).

Does this work well with dry food?

Answer by Chewy • Apr 06, 2024
Felisyl L-Lysine granules are typically flavored to be palatable for cats, making them easier to administer. The granules can be sprinkled over dry food, mixed with wet food, or given directly to the cat. This convenience allows for hassle-free supplementation.
Reviews
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4.3
Rated 4.3 out of 5 stars
170 Ratings
Terms & Conditions

Customers Mention

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

Effectiveness

80% Positive

Form and Administration

71% Positive

Ingredients

80% Positive

Nutritional Value

84% Positive

81 Customer Reviews

Rated 4 out of 5 stars
By Elizabeth on Jan 1, 2026

Helped the sniffles

I got this after a recommendation from a friend after I mentioned my 2 rescue kittens seemed to sneeze fairly often regardless of how much I dusted, used fragrance

I got this after a recommendation from a friend after I mentioned my 2 rescue kittens seemed to sneeze fairly often regardless of how much I dusted, used fragrance free detergents and cleaners etc. very mild but occasional sneezing and one has a chronically crusty nose. I’ve noticed lately after about 5 weeks of using this we have very few sneezes now, and the crusty nose has improved a lot. The only downside is I can’t hardly even give them 1/4 of the serving because it gives them diarrhea but it is still helping even in such a small serving. Hopefully after more their tummies can handle more

Rated 1 out of 5 stars
By Jennifer on Nov 30, 2025

Can't trick them

My cats refuse to eat when I added the full dose but then I cut it in half and they ate a little. I think they can taste the difference. If your cats are divas I

My cats refuse to eat when I added the full dose but then I cut it in half and they ate a little. I think they can taste the difference. If your cats are divas I would try something else.

Rated 5 out of 5 stars
By Thomas on Jul 24, 2025

Easy to administer!

This so easy to administer to my cats simply to mix in with their favorite treats. With a fork I stir it in a small dish with a portion of their favorite wet food

This so easy to administer to my cats simply to mix in with their favorite treats. With a fork I stir it in a small dish with a portion of their favorite wet food treats such as squeeze ups. It is easily portioned with the small measuring spoon that comes with the FELISYL.. It is noticeably helping to resolve respiratory issues such as sneezing in one and coughing in another of our cats.

Rated 5 out of 5 stars
By Rose on Sep 30, 2025

Quick delivery

This supplement was easy to order for my cat to boost his immune system after going blind. We received it quickly. Reasonable prices with Chewy.

This supplement was easy to order for my cat to boost his immune system after going blind. We received it quickly. Reasonable prices with Chewy.

Rated 1 out of 5 stars
By Helen on Jul 31, 2025

Did not help

This brand unfortunately did not help my cat at all. I had switched from Vetriscience brand to see if cat would like the taste better, but it did not work out and

This brand unfortunately did not help my cat at all. I had switched from Vetriscience brand to see if cat would like the taste better, but it did not work out and now I have to throw it away.

Rated 1 out of 5 stars
By Vincent on Nov 29, 2025

Nothing

Did not help my cat in any way. I threw it away.

Did not help my cat in any way. I threw it away.

Rated 5 out of 5 stars
By Judy on Apr 30, 2025

Is helping my cats

Upon my mother’s death, I inherited six of her outside cats. These cats were not in the best of health and were also somewhat feral. I did take some of them to the

Upon my mother’s death, I inherited six of her outside cats. These cats were not in the best of health and were also somewhat feral. I did take some of them to the vet who told me that they had some kind of a chronic upper respiratory condition that was common among some cat colonies. They had sniffles and sneezing. Some of the cats were worse than others. I have incorporated Felisyl into their daily feedings and it has helped each of the cats by cutting down, and in some cases eliminating, their runny noses. You can tell that they are all feeling better and they have now accepted me and their new living arrangement. Thank you, Chewy!

Rated 5 out of 5 stars
By Larry on Dec 10, 2025

Helpful

Helped with sneezing issues. Grateful.

Helped with sneezing issues. Grateful.

Rated 5 out of 5 stars
By Jean on Jul 28, 2025

Sneezing

My cats sneeze a lot. Not because of a dusty house I truly believe it’s the Tidy Cat Litter dust. I switched litter to a 99.9% dust free.

My cats sneeze a lot. Not because of a dusty house I truly believe it’s the Tidy Cat Litter dust. I switched litter to a 99.9% dust free.

Rated 1 out of 5 stars
By Patti on May 20, 2025

Disappointed

This is ground so fine that it didn’t stick to my cats’ dry food like the Viralys. When the food was gone, this was all at the bottom of the bowl, so I don’t think

This is ground so fine that it didn’t stick to my cats’ dry food like the Viralys. When the food was gone, this was all at the bottom of the bowl, so I don’t think they even ingested any. I’m going back to Viralys.