NOW PETS L-Lysine Immune System Support Cat Supplement, 8-oz jar -

NOW Pets L-Lysine Immune System Support Cat Supplement, 8-oz jar

By NOW Pets
Rated 4.3883 out of 5 stars
$14.00Chewy Price
$15.99Chewy Price
$13.30Autoship Price
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About This Item


  • Developed to easily provide L-Lysine to your feline companion.
  • Supports respiratory and ocular health as well as a healthy immune system.
  • Purr-fect for multiple-cat households or boarding needs.
  • Veterinarian recommended to support your four-legged friend.
  • Certified by the by National Animal Supplement Council.

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Nutritional Information

Feeding Instructions


Questions & Answers

8 Customer Questions

Will this harm my cats if I feed it to them more then two times a week?
Answer by ChewyMar 19, 2022
Results from two clinical trials with cats suggest that excess dietary lysine may have an enhancing effect on FHV-1 replication, so some caution is suggested in supplementing. This newer evidence recently led NOW Pets' veterinarian formulator to recommend lowering the serving frequency, which they changed on their label over 8 months ago. One suggestion would be to pick specific days - for example, Wednesday and Sunday - to add the supplement. If you have any further questions please discuss with your vet.

How many servings does this jar have?
Answer by ChewySep 10, 2022
NOW L-Lysine for Cats has a varying number of servings, depending upon weight. For cats up to 5 3/4 pounds, give 1/16 teaspoon twice weekly. For cats over 6 pounds, give 1/8 teaspoon twice weekly. Using a 1/8 tsp (276 MG) serving, divided into the total weight of 226.8g = 821 servings. If giving to a smaller cat (1/16 tsp) it would have twice as many servings. If using for one cat, twice weekly, as suggested, one bottle would last for years.

Can you put the powder on dry food?
Answer by ChewyMar 24, 2018
This supplement should be administered during or after the animal has eaten to reduce the incidence of gastrointestinal upset. It can be added to their dry or wet food.

How long until l-lysine starts to suppress and alleviate any symptoms a cat may be experiencing?
Answer by ChewyJun 11, 2020
NOW Pets L-Lysine Immune System Support Cat Supplement supports a healthy immune system. There is no time frame in supporting the immune system.

ReviewsWrite a Review

Rated 4.3883 out of 5 stars
103 Reviews
Would recommend to a friend

103 Customer Reviews

Filter by reviews that mention

Rated 5 out of 5 stars
By angelize on Mar 4, 2023

Great stuff

I have been giving my indoor cats 1/8 tsp of this every morning with their wet food. Absolutely no taste so cats don't even notice it. More importantly, I take care of 3 feral cats and being outside with other cats makes them more susceptible to URI's. In the 3 years that I've been feeding them, this goes in their food every day and I have never seen one of them with running eyes or sneezing. It is reasonably priced and easily mixable. I am very pleased with the results!!

Rated 5 out of 5 stars
By Claudia on Jan 18, 2023

Overly sensitive cat's

Dr Barbara Royal, DVM. This has been miracle to Kiki I felt like a failure when I adopted him. The food, certain types of materials even flea collars would leave tiny sores. He luvs the Now l-lysine high protein pate's and Johnson & Johnson baby powder for his itchy skin. It's been a battle ... Thank you from the bottom of my heart!

Rated 5 out of 5 stars
By Darkstar on Nov 25, 2022

Vet recommended, human pleased

Our vet recommended putting our kitties in Lysine. The one i was buying was almost $30 for a small jar. I searched chewy and found the Now brand for a third ofthe price n had more ounces. My kitties love it, their huma. Highly recommends this brand !!!

Rated 5 out of 5 stars
By BrianW on Oct 30, 2022

Cat with runny nose, eyes, wheezing

A young male cat adopted me 4 months ago. He has been wheezing and had discharge from his eyes and nose with sporadic sneezing ever since. I had a vet administrator a injection (don't know what kind) for possible correction to no avail, so my internet research led me to this L-Lysine granulated product. I (self prescribed) 250mg 2x/day mixed in with soft cat food available from Chewy topped on top of dry Kibble. After the 1st 4 days I noticed improvement. It's been 16 days at the same dosing and frequently and I'm continuing to see improvement. I forgot to mention that his stools were also loose until this morning when it now appears solid and closer to normal. I will eventually tapper the frequency of doses as he recovers so as not to cause any possible damage or dependency. Again this is solely at my own judgement and risk. I did not choose this under the advice of a vet. I am not a Licensed veterinarian and advice others to use their own judgment at their own risk.

Rated 4 out of 5 stars
By Snail on Aug 19, 2022

Feline Herpes Remedy

My boy has Feline Herpes and I use Lysine to help with his symptoms. This is the only Lysine he will eat to date with no worries! I just put it on his food and it’s he’s to go :) The only criticism is that the dosage is twice weekly at 258mg. Cats can actually have up to 500mg a day of Lysine and I noticed with this dose I wouldn’t really get good results. I spoke to my vet for some more incentive and she recommended to give him a higher dose weekly to help. I am hopeful it will work if I give him a higher dose because this is the only Lysine he will eat! So if your pet has Feline Herpes I would ask your vet for more information on what is a more appropriate dosage than the label on the back of the bottle!

Rated 5 out of 5 stars
By Babynyc on May 31, 2022

Terrific supplement

I use a 1/4 teaspoon and put only half of that in to make the 1/8 teaspoon twice daily. I mix it with my Baby's wet food and water. She doesn't know it's there, or she's pretending not to know, she eats it all. I mix it really well though, perhaps people not having luck should try a bit more mixing... I will buy this again when we run out, her mood has improved and her coat is shiny and she's not doing her normal hotspot biting anymore either (she was a shelter rescue and came with her own sweet but sad little issues).

Rated 5 out of 5 stars
By Bear on Jun 28, 2022

Great Product

At a great price, was recommended by my cat's vet to help his immune system with the Feline Herpes Virus he acquired while in the animal shelter I adopted him from. Seems to be working when nothing else did.

Rated 1 out of 5 stars
By Echo on Jun 1, 2022

Cats did not like.

I like the idea of giving pure lysine without any other ingredients. Both cats would not finish their food when this is mixed in. Will try another brand.

Rated 5 out of 5 stars
By Moffa on Apr 23, 2022

Healthy Kittens

I’m fostering again. Think 11 sneezing, runny noses and sets of watery eyes. Vet recommended L-Lysine as immune support. Success! It barely took a week and mixing it in their food made dosing easy. Just do what vet tells you.

Rated 4 out of 5 stars
By mole on May 28, 2022

check with your vet first

While this product has pure l lysine in it and that is a good thing.It was formulated by the companies vet.The dosage is extremely low .Certain cats need a stronger dose .What ever dose your vet recommends go by that .