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  6. Felisyl L-Lysine Immune System Support Granules for Cats (3.5 oz)


Felisyl L-Lysine Immune System Support Granules for Cats (3.5 oz)

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Felisyl is a supplement that contains the amino acid L-Lysine for use in cats and kittens for conditions responsive to L-Lysine. L-Lysine is an essential amino acid, which means that your cat's body needs it, but can't produce it, so this supplement is a perfect choice to provide that necessity.

L-Lysine HCL Immune System Support for Cats helps keep your cat healthy by supporting the immune system naturally so that it can function normally and produce antibodies. Felisyl L-Lysine HCL Immune System Support for Cats also helps maintain healthy tissue, supports respiratory health, and may even help with your cat's vision. The L-Lysine is in palatable poultry, and the flavored fish base was making these granules easy to give to your cat, sprinkle over or mix with food.

Key Benefits:

  1. Enhanced Immune Function: Lysine is an essential amino acid that plays a crucial role in supporting the immune system of cats. Felisyl L-Lysine granules provide a concentrated source of L-Lysine, which helps strengthen the immune response, making cats less susceptible to various viral and bacterial infections.
  2. Cold Sore and Feline Herpes Relief: Lysine is commonly used to manage feline herpes virus (FHV-1) infections, which can cause symptoms such as cold sores, sneezing, watery eyes, and nasal discharge in cats. Felisyl L-Lysine granules help alleviate these symptoms and reduce the severity and duration of FHV-1 outbreaks.
  3. Support for Respiratory Health: FHV-1 infections often affect the respiratory system in cats. By boosting the immune response and reducing viral replication, Felisyl L-Lysine granules can help improve respiratory health, decrease congestion, and alleviate breathing difficulties associated with respiratory infections.
  4. Minimizes Lysine Deficiencies: Some cats may have dietary deficiencies or require additional lysine due to various factors, such as stress, poor appetite, or certain medical conditions. Felisyl L-Lysine granules ensure an adequate supply of lysine, which is essential for the production of proteins, enzymes, and antibodies, thereby supporting overall feline health.
  5. Palatable and Easy to Administer: Felisyl L-Lysine granules are typically flavored to be palatable for cats, making them easier to administer. The granules can be sprinkled over food, mixed with wet food, or given directly to the cat. This convenience allows for hassle-free supplementation.

It's important to note that while Felisyl L-Lysine Immune System Support Granules provide valuable support for feline health, it's always recommended to consult with a veterinarian before starting any new supplement regimen for your cat. They can provide specific guidance tailored to your cat's individual needs and overall health.

Immune Support for Cats

Fuel your pet with the supplements they need to remain healthy and boost their immune system with cat health supplements that add much-needed nutrients and amino acids to continue being active.


L-Lysine is an essential amino acid that your pet?s body doesn?t produce, so this supplement is the perfect aid that helps support your pet?s immune system so that it can function normally and produce antibodies. L-Lysine also helps maintain healthy tissue supports respiratory health.

Pet Health Supplement

A healthy immune system and eye health are essential for cats of any age. Ensure your furry friend remains active with healthy vision with these pet health supplements that help support normal inflammatory response and help support cat-eye health.


Guaranteed Analysis (Per 1cc Scoop):
L-Lysine HCI 250mg


L-Lysine in a palatable base

Useful Information

Approximately 250mg of L-Lysine per one rounded scoop (322mg)

Kittens under 6 months: ½ Scoop twice Daily

Cats older than 6 months: 1 scoop twice daily

Store in a cool, dry place, out of the reach of children. Keep tightly shut to preserve freshness.

Customer Reviews

Review Summary
30 Reviews
70% (21)
20% (6)
3% (1)
3% (1)
3% (1)
90% Recommend this product (27 of 30 responses)
By Karin T.
November 28, 2020
I have been buying this for years. I am with an animal rescue and using this product in the kitten wet food AND adding a pinch when I have bottle babies (even a kitten i rescued at 1 day old) NONE of my kittens ever got sick and my bottle babies thrived and grew up to be healthy adults. I continue to use for my adult cats and recommend my adopters to continue using for their new adopted kittens cats. And all have continued be healthy (along with YEARLY WELLNESS EXAMS and necessary vaccines!) And this product also helps my cats with eye herpes (weepy eyes) and special breeds with weepy eyes. As a cat rescuerer I HIGHLY RECOMMEND this product!!!

Merchant Response:Karen, Than kyou for your review of Felisyl. The pictures are excellent and bless you for the work you do with these felines.
  • None
By Chris
Easy to use.
April 9, 2018
My cat has been taking this product for several years as prescribed by his veterinarian.
By gm t.
Great Benefit to my pets
November 16, 2016
Excellent product to boost the immune system for my cats. I've used this product for almost a year and I've seen improvements.
By Angie
Whittier, CA
Better than another
October 21, 2016
I tried this L-Lysine product because I didn't see my regular one listed, and to my surprise this one looks and works better!
By purplemoe716
Alpine, Texas
Glad I bought this product
August 1, 2016
I have 3 cats who have issues with eating solid food. I mix hills science diet a/d with chicken broth, evaporated milk and water. I think this product is helping all 3. I know for sure one does have the rhino virus and just assume the others do as well. All seem to look forward to eating their gruel with this added to it..
By NJMalan
central NJ
Felisyl flaors a no go with my cats!
July 20, 2016
The flavor is something none of my cats will eat as I mix it in their food and they just go hungry without eating it. I would have preferred a non-flavor one.
By sharona0695
cat wouldn't eat
June 30, 2016
my cat refused to eat her food when I mixed it with her canned food. It would be better if it came in an unflavored version.
By ceedee847
Walnut Creek, CA
April 25, 2016
After my cat was diagnosed with FHV in 2010 I read about the benefits of lysine and have been using it since. Have not had another episode of FHV since. I give him lysine power and chews twice a day. The Felisyl mixes well with his canned food and he has had no problems.
By Robb
Phoenix, AZ
Perfect Solution
April 12, 2016
One of my cats suffers from feline herpes which seriously affects his eyes. The Felisyl Immune System Support Granules completely eliminates the symptoms from the herpes virus, as well as the depression he suffers when the herpes symptoms do occur. With using the Felisyl, he only has a brief and mild occurrence once or twice or year. He's a happy cat with a happy owner.
By KatzenMutter
Improvement within days
October 5, 2015
One of my cats has had frequent eye troubles (discharge, crustiness, wincing) which the vet has attributed to her having had a bad upper respiratory infection years before she "adopted us". Within days of adding this powder to her food, her eyes have cleared up entirely. Who would have guessed?
By brit
my vet recommended
April 22, 2015
Vet recommended adding Lysine to cat's food and my cat seems to enjoy food.
Depew, NY
Felisyl Immune System Support
March 11, 2015
Yes it does work well. We have two cats and they like, but make sure that you mix it well in the food.
By Bruiser
Great product
April 13, 2014
When shopping for a Lysine supplement for my FIV positive cat I had been used to the Viralys gel. Seeing as how the Felisyl brand was half the price I thought I'd give it a go. I feel that the powder allows me to be more accurate in the dosage. And my cat has transitioned very well. I will definitely be back for more when my supply runs out.
By foxfyreutk
Kitties Are Crazy for It!
December 31, 2013
I had been mixing granules into canned cat food, but that is a very expensive treat. Thought I would try the kitty treat version. Both my cats are crazy for it. They try to open the bag themselves and remind me it's time for their treat. Far easier and not nearly as expensive as the powder.
By FosterMama
Good product!
September 24, 2013
Easy to give to kitties with a little bit of wet food or even add a little water. My cats love it and it keeps their sniffley episodes down. Love it!
By kirvls
My Ferals Like It
September 17, 2013
They like the flavor and it gives them the Lysine they need.
By Buddy
Jackson, TN
Only product to help my pet.
August 21, 2013
This is recommened by my vet. Only thing that can build his imm. system
By cathy
it works great
August 20, 2013
my cats caught the feline cold from a new cat I got they were all sick. I looked up what to give them to help them. this is the lysine and its in this product works great to keep it under control, nobody has gotten sick again . I put it in there food and they don't even know they are eating it.
By jj
May 20, 2013
works really great it really helped and looking forward to ordering more in the future
By Sandy
New York
December 14, 2012
Used the product for my cats who were sneezing and it seemed to help them a bit. Their eyes are no longer dripping as they were, so perhaps it works as stated.
By Karen
my cats love this
November 30, 2012
this product is very palatable, one of my cats even tries to lick it right out of the jar!
By Katzhse
Tucson, Az
Review for Felisyl Immune System Support Granules (3.5 oz)
November 24, 2012
I have been sprinkling this on their dry food so at least they get some when they eat. If i put it in the wet food they won't eat it.
By Queen B.
New Castle, DE
Felisyl Immune System Support
November 23, 2012
It seems to work as well as other brands. It dissolves better in food than other brands. It's slightly cheaper, however, I believe the dose is slightly larger.
By Kaye63
Good stuff!
November 13, 2012
My cats loved this and I will be ordering it again!
By moms_2slow
Wilton, CA
Works very well
August 16, 2012
This product has a very yeasty smell, so my cat loves it. He has slowly improved on the product, so I am quite happy.
By max's m.
west palm beach
product probably fine but the cat won't get near i
April 5, 2012
They say it is flavorless and odorless. The cat doesn't think so. Right now I am back to crushing human lysine tabs and then mixing them into soft food to hide it. Right now, that is fine but may try sneaking this into his soft food again soon to save me the trouble of mashing his pills. Too early to tell how this will work.
By Dawn
New York, NY
Good product
March 10, 2012
I used to buy a more expensive brand, then found this one. The color turned me off a little (I'm used to a white powder), but my cat doesn't know the difference and I have no problem putting it in her food.
By Benji's m.
Review for Felisyl Immune System Support Granules (3.5 oz)
March 4, 2012
The cat loves his food with sprinkles of FeliSyl on top and has zero hair balls if given daily.
By Debi
Woodbridge, VA
Felisyl Immune System Support
March 4, 2012
My cat does not like "treats" so I bought the powder version of Felisyl and put it in his food. He does not know the difference and he eats it! YEAH!!! No force feeding!!!! Something you do not want to do with a cat. (CLAWS)

I will definately be buyng more in the future!
By Barb
Review for Felisyl Immune System Support Granules (3.5 oz)
December 3, 2011
I give this to my 4 cats on a daily basis. Very pleased with results.

Questions and Answers