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Felisyl L-Lysine Immune & Respiratory Support Salmon Flavored Gel for Cats & Kittens, 5-oz tube

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At a Glance

  • Immune Support
  • Eye Care
  • Kitten
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About This Item

Details

  • Powered by L-lysine, an essential amino acid that promotes healthy antibody levels, this supplement is ideal for cats prone to FHV-1 flare-ups, seasonal stress, or general immune challenges.
  • It helps ease sneezing, runny nose, congestion, and watery eyes associated with common upper respiratory issues, perfect for cats in need of gentle respiratory support or allergy relief.
  • Great for picky eaters and kittens, the smooth, salmon-flavored gel is easy to place on your cat’s paw, nose, or dish for fuss-free daily dosing.
  • Vet-formulated and recommended to deliver targeted immune, respiratory, and eye health support, this L-lysine gel is safe for daily use in kittens, adults, and senior cats.
  • Made in the USA and manufactured under rigorous quality and safety standards, this high-quality supplement offers consistency and peace of mind with every dose.

Ingredient Information

Instructions

FAQ

Learn More About Felisyl From Our Team of Experts

Felisyl L Lysine Immune System Support

Felisyl L Lysine is formulated to support normal respiratory health and overall wellbeing in cats. Known for its immune supporting properties, L lysine helps maintain 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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Questions & Answers

3 Customer Questions

How many servings per tube?

Answer by Chewy • May 01, 2025
The total content of the Felisyl-Gel tube is 142 grams, which equals approximately 25 teaspoons. Each dose is a portion of a teaspoon. For Kittens under 6 months of age, give ¼ teaspoon twice daily. For Cats 6 months or older, give ½ teaspoon twice daily.

Does it comes in a different flavor

Answer by Chewy • Mar 19, 2026
The Felisyl brand L-Lysine Immune & Respiratory Support Gel for Cats & Kittens is only available in a salmon flavor. Felisyl chicken-flavored soft chews and liquid concentrate are available.

Can this be added to wet food?

Answer by Chewy • Sep 29, 2025
The manufacturer recommends administering orally. A small amount can be placed on your cat's nose to stimulate taste interest. Once interest has been established, a syringe or teaspoon may be used. It can also be applied directly on cat's paw to allow cat to lick off.
Reviews
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4.4
Rated 4.4 out of 5 stars
570 Ratings
Terms & Conditions

Customers Mention

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

Ease of Use

83% Positive

Effectiveness

83% Positive

Ingredients

86% Positive

Long-Term Benefits

84% Positive

243 Customer Reviews

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

Ernie loves the taste!

I was worried Ernie wouldn’t like this because he’s not a salmon fan but he eagerly kicks this up. I squeeze it on my finger and he licks it off. He won’t let me

I was worried Ernie wouldn’t like this because he’s not a salmon fan but he eagerly kicks this up. I squeeze it on my finger and he licks it off. He won’t let me out it on his paw nor will he touch it if I squeeze into a saucer. I’ve not seen an improvement yet with his eyes but maybe it’s too soon to tell. What I really need to do is get him to the vet to make sure there isn’t something more serious going on.

Rated 4 out of 5 stars
By Loki on Nov 30, 2025

Inconsistent thickness

It works excellently for my cat's stress-induced feline herpes as well as usually being great for coating pills for both of my cats. The consistency is unpredictable,

It works excellently for my cat's stress-induced feline herpes as well as usually being great for coating pills for both of my cats. The consistency is unpredictable, though. Sticking it in the fridge helps to firm it up, but it's not supposed to be as watery as it is sometimes. The consistency has not had an effect on how well it works, but does effect how willing my cat is to actually want to take it. When it's thicker he will lick it from an oral syringe or off of a plate like it's a treat, but when it's thin he avoids it and it tends to melt pills unless it's straight out of the refrigerator. It's not Chewy's fault, the manufacturer needs to do more quality control. It does work either way, though, and hasn't made my cat sick or anything. It helps keep his runny, itchy eyes from turning into another bout of pneumonia, so definitely worth the price. Also, the salmon flavor is much preferred over the maple one (at least with my cats). I suggest getting 3ml oral syringes that come with caps if you buy this. They make it way easier to measure, administer, and refrigerate as needed.

Rated 4 out of 5 stars
By Jacquie on Dec 3, 2025

Cat enjoys it, wish it worked a bit better

My cat actually likes the flavor of this which is shocking as she's very picky. The consistency is very watery so it'd be easier to administer in a syringe but I

My cat actually likes the flavor of this which is shocking as she's very picky. The consistency is very watery so it'd be easier to administer in a syringe but I just goop some on my finger and wipe it in her mouth. She'd lick it up herself but she knows a treat is coming after and will snub it for that. This was for her herpes and allergy flare ups and in the past lysine knocked it out within a week. I'm going on 3 or so weeks and her flare is reduced but still there. She's also on a steroid which I think is doing the bulk of the work. Since it's easy to give her and she likes it I'll get a second tube and continue!

Rated 5 out of 5 stars
By Paigelynn on Dec 12, 2023

Cat loves it! results in about 2 weeks

Our cat tested positive for Feline herpesvirus (FHV). Since she was a kitten, she had issues with having a lot of eye discharge that came in waves. It got worse,

Our cat tested positive for Feline herpesvirus (FHV). Since she was a kitten, she had issues with having a lot of eye discharge that came in waves. It got worse, like a pink-eye status. Crusted shut. While waiting for a vet appointment, (we flushed her eyes daily with Microcyn wash after applied warm washcloth/wiping)... we hardly saw improvement until we got the L-lysine gel product. **She takes it as a routine treat! Looks forward to it nightly, and in about 10-14 days, she had exponential improvement in her red, and mucus-clouded eyes. We were able to cancel the vet appointment, and it seems to help a lot!

Rated 5 out of 5 stars
By Aleita on Jun 18, 2025

Palatable for picky cat

We mixed this in with our cat's wet food and he ate it no problem! Be aware, lysine can cause stomach upset in cats. We gave our cat (adult, male, 13lbs) 1/4 tsp

We mixed this in with our cat's wet food and he ate it no problem! Be aware, lysine can cause stomach upset in cats. We gave our cat (adult, male, 13lbs) 1/4 tsp a day, and within a few days he was vomiting. This resolved after discontinuing the lysine gel. Unfortunately, he's a smart cat, so he won't eat it anymore. Still 5 stars because this has nothing to do with this particular formulation or product, it's just the nature of lysine supplements. Our cat also has a sensitive stomach. You might have better luck!

Rated 5 out of 5 stars
By Cait on Dec 30, 2024

Have only been using a week or so..

So can’t be sure, but in the past week my sweet little gal has fewer “agitated” moods. She was feral when I found her at 6 mos old this past summer, and with food,

So can’t be sure, but in the past week my sweet little gal has fewer “agitated” moods. She was feral when I found her at 6 mos old this past summer, and with food, string toys, and lots of patience was able to get her inside in August. She has adapted well to indoor life so far but still has occasional mood swings and tantrums. Has been very chill all week tho. I found out a month after bringing her in that she has feline leukemia so I worry a lot for her. One thing thats recommended to keep her immune system up is L-Lysine, but I made a mistake months ago and bought the powdered version which is difficult to give her. She no longer likes wet food so I couldn’t just add to that and oddly has gotten insatiable abt her dry Iams. (If I’d have known she was going to become food addicted so suddenly I would’ve researched the perfect food for her, but at least she seems to be doing well on the Iams Pro Health so far.) In any case, I can’t get her to eat anything else besides the Iams now EXCEPT for: churu treats (which I’ve only just discovered), temptation treats (which I no longer give rlly) and this! She LOVES this. I just give her a dab on my finger once or twice a day and it’s so much easier than loading the powder in a syringe with water and scaring her half to death holding her head still. This is much easier, makes her happy, and I rlly do think it’s already having some positive affect. I could be wrong but even if so, it’s at least not making her sick and I’ve seen no ill affects, so hope it helps my girl stay healthy! Thanks Chewy!

Rated 5 out of 5 stars
By Amanda on Nov 29, 2023

Works better than the powder for my cat

I’ve been using Lysine powder for a couple of years for my cat with a chronic runny eye. The powder I usually get was unavailable this time so I tried this stuff

I’ve been using Lysine powder for a couple of years for my cat with a chronic runny eye. The powder I usually get was unavailable this time so I tried this stuff instead. It works great! After a couple days of use, his eye is all cleared up! I’ll be buying this from now on. He was a little hesitant to eat it at first, I had to wipe it on his paw the first couple times for him to lick off. Now he likes it and comes running when I get it out.

Rated 5 out of 5 stars
By Maya on Jun 26, 2025

Good for Feline Herpesvirus

My cat Chico caught feline herpesvirus which appears as red eyes, runny eyes, and sneezing in him. The vet recommended I put him on Lysine. I tried some other ones

My cat Chico caught feline herpesvirus which appears as red eyes, runny eyes, and sneezing in him. The vet recommended I put him on Lysine. I tried some other ones before however he was very against them. However he is IN LOVE with this. He was a picky eater however now every time he sees the bottle he goes crazy for it. The paste is also working good at clearing up all of his symptoms. Great product.

Rated 5 out of 5 stars
By Laura on Nov 14, 2025

Sneezing is gone

Something for my cat's allergies and he loves the taste. He is picky too. His sneezing has subsided since he has taken this and it happened pretty fast. He has had

Something for my cat's allergies and he loves the taste. He is picky too. His sneezing has subsided since he has taken this and it happened pretty fast. He has had a sneeze problem for over a year with snot coming out, eww. He doesnt have either, anymore, since taking this supplement.

Rated 3 out of 5 stars
By David on Nov 1, 2025

Cat didn’t love it

I was excited to try this because I had only ever found maple-flavored lysine before, but my cat’s response was unimpressive. I was really hoping he’d like it as

I was excited to try this because I had only ever found maple-flavored lysine before, but my cat’s response was unimpressive. I was really hoping he’d like it as much as the fish-flavored hairball paste, which he and my other cat love so much they’ll lick it right out of a bowl. Unfortunately, I still have to stick this in his mouth. At least I’m pretty sure he doesn’t mind the taste, but I was really hoping I’d found another product I wouldn’t have to administer manually.