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  6. Felisyl L-Lysine Immune System Support Granules for Cats - 3-PACK (10.5 oz)


Felisyl L-Lysine Immune System Support Granules for Cats - 3-PACK (10.5 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
28 Reviews
71% (20)
18% (5)
11% (3)
0% (0)
0% (0)
93% Recommend this product (26 of 28 responses)
By ChristineP
Dover, NJ
July 16, 2017
My cats would not eat their food with this added. Bought 3 jars, unfortunately threw out the shipping receipt so I can't return it. Will have to order the other brand.
By Cease
Northern Colorado
Seems to be a good product
May 7, 2017
Felisyl seems to help keep in check the stomatitis virus two of my cats have. Combined with Geneflora, we have managed to not have to have our cats teeth extracted, a very costly procedure. I would recommend only mixing with fish canned food as they didn't like it mixed in with poultry or beef canned food, bc it is fish flavored.
By snoopy26??
great product
July 21, 2016
I have 2 cats with chronic URI so I put some in their canned food each night and they all eat it with no issues. I believe it helps them.
By Pam
Clinton, TN
Good results so far
December 17, 2015
Purchased this product for a friend who is fostering a feral momma cat and her kittens. The momma suffers from a herpes virus that was very severe in her eyes. This product seems to have cleared it up within days. We had to try something that could be added to her food since she can not be held and given meds.
By Max's m.
Atlanta, GA
good product
September 15, 2015
I have 3 cats, 2 with feline herpes. the lysine really helps keep the herpes respiratory virus under control and avoid rounds of antibiotics for the cats.
Works well and more economical
July 24, 2015
Felisyl (L-Lysine) immune system support is effective in controlling symptoms of feline herpes (e.g. eye discharge, sneezing) among those cats of ours showing these signs. The product is readily ingested by our cats when we mix it with their morning and evening wet food. When we miss a day or two, the symptoms return but are quickly resolved upon resuming the dosages. At the recommended dosage, Felisyl is more economical to use than other equally effective l-lysine products.
By Ty
Love it
June 14, 2015
Delivered very prompt always, only place we get our cats products. Thanks for your great prices also. Ty
By CatLady51
Lima, Peru
My cats don't like it!
May 15, 2015
To my dismay, my cats do not like the product. They deliberatedly leave the wet food that has it!
Too bad,
By Lee
No smell at all - great for hiding in food
April 16, 2015
Was pleasantly surprised when I opened the container to find there was no smell to the powder crystals. The product this was comparable to has a nasty dead fish smell. This one did not. Thank you for a great product.
By Kim
Cats love it
April 14, 2015
I've tried the chew treats and my cats hate them. This I mix in their wet food every morning and they eat it right up. Theirs eyes have cleared up and the sneezing is to a minimum.
By vnapper
Great for Feline AIDS kitty
March 20, 2015
I add this powder to all of my kitty's food. It helps keep their immune system up and prevent problems. I have a Feline AIDS positive kitty who gets this in all of his meals. I really notice a difference in his breathing (wheezing) and his overall playfulness. I also add this to my other kitty who has an eye infection and it helps her fight that. Great stuff.
Northern Illinois
Great Supplement
March 3, 2015
I purchased Felisyl Immune System Support for my newly adopted elderly kitty (12 years old), who has extreme allergies. I switched her from all food with wheat and corn, added Omega 3 oil to her wet food for her very dry skin, and am adding the Lysine supplement to her diet in hopes of keeping her allergies at bay. She hasn't been on it very long, but I'm looking at the long term for her. The first week she was here, she nearly literally choked to death on the copious phlegm in her throat. The vet told me to use children's Benadryl to help her out, and that seems to help, but I want her off meds if at all possible. The lysine will help with her immunity and it's also something the vet suggested. I'm looking forward to a healthy kitty now!
By Teddy's m.
Northern California
Good product
February 16, 2015
This supplement was recommended for my cats. They seem to like this brand better than the one I purchased at the vet. The price is better too.
By Kazuye
Los Angeles
August 17, 2014
My cat caught the herpes virus while a kitten at the animal shelter. Felisyl helps her from getting so much sneezing and stuffy nose symptoms. I mix it into her food everyday and she doesn't mind it at all.
By dustyj
austin, TX
great product
February 26, 2014
I have a cat with a chronically irritated eye and she is also FIV positive. My veterinarian had suggested l-lysine to help decrease the viral load and she suggested this. I sprinkle some on a bit of wet food or spray water on her dry food and sprinkle some on it. She gets her doses twice a day - no hassle.
By mindymoon
not just for feline herpes
December 14, 2013
I took in a very sick stray 3 years ago He had an upper respiratory infection so severe that 3 different vets weren't sure he would make it. He also tested positive for Feline HIV. Vet suggested Viralys for immune support. I've had him on Felisyl for 3 years. After months of TLC and antibiotics, he got healthy and gained weight. His coat is beautiful, eyes and ears clear. And he has stayed very healthy since. I think the Felisyl helps, so will continue it for the rest of his life. I add a scoop to his wet food once a day.
By cati
Excellent purchase price
August 7, 2013
This L-Lysine HCI supplement for cats is less expensive than the vet recommended Viralys. So far, it has been just as effective to address herpes in my cats. The best part about Felisyl is that the cats actually eat it readily when mixed with canned cat food.
By I n.
North Carolina
Felisyl Immune System Support
July 1, 2013
The cats like it, Use it to help keep foster kitties healthy.
By DustyJ
elgin tx
Great product
June 15, 2013
Cats like the lysine powder (all 9 of them) - a first! easy to put on wet or dry food. I use a slight spray mist of water which helps the powder stay attached to the dry food and voila it is eaten without problems
By Kazi's M.
Review for Felisyl Immune System Support Granules - 3-PACK (10.5 oz)
June 7, 2013
This product has done a good job keeping my kitties from having feline herpes return. It is a good immune system builder.
By annetta
This is Great Stuff!
March 29, 2013
Felisyl helps the immune system of cats. My cats have frequent sneezing and it takes care of it. Likely the vet said it's probably from cat herpes. But many cats have this. Any time a respitory problem...cold or stuff like that starts...give them felisyl. It's best to not give daily unless your cat has a severe or ongoing problem. It works for my babies and it may likely make your vet trips much less needed.
By Tutti
Los Angeles
Felisyl recommended by my vet
February 6, 2013
Great product especially for those of us that have more than 1 cat because you can use it every day in their food and it strengthens their ammune system. I am on my 4th container. Entirely Pets has the best price according to my vet.
By Tuxcats
good value
December 17, 2012
There are other L-Lysine products, same ingredients, at a higher cost, on the market, and at the Vet's office. Happy with product, price, and great service.
By vj
Very nice product
December 14, 2012
My cats must like the taste because they eat it up when I sprinkle it on their food!
By fostercatmom
Indianapolis, IN
great stuff
August 19, 2012
I have volunteered with an animal shelter for over 10 years. We put lysine on the food of all the cats because it helps with the herpes virus that runs through all shelters. It doesn't cure the virus, just helps to keep it from replicating. This version is flavored and the cats like it.
Essex County, NJ
Good Supplement for Those Who Need It
April 10, 2012
My vet told me to add lysine to my cat's food. He had a herpes infection when I rescued him. The lysine is supposed to help recurrences and thus far Simon has had none.

I mix the Felisyl with his wet food and he seems quite willing to eat it. It's easy to use and one jar lasts for a couple of months. Good product.
By Cat L.
Review for Felisyl Immune System Support Granules - 3-PACK (10.5 oz)
March 23, 2012
Have had the cats on this for years to keep down the symptoms of the kitty herpes type illness. They like the taste and it works well. Much easier to use than the paste and more economical too.
By MaryAnnSanDiego
San Diego, CA
My cat liked the Viralys better
July 6, 2011
I had been using the Viralys powder for about a year with no problem. Just decided to try the Felisyl since it was a little cheaper. My cat backs away from ANY food I put down with the Felisyl mixed in. Eventually after complaining for a while, she will eat! I will go back to the Viralys so I won't have any food issues. Both products seem to work the same, however.

Questions and Answers