Skip to product information

L-lysine Immune Support Chews for Cats

L-lysine Immune Support Chews for Cats


L-lysine Cat Powder provides the amino acids essential for antibody production to promote normal immune system response and help fight infection. 60 Chews. Salmon Flavored.
Orders placed before 12pm EST ship same day with free shipping.

Product information

Immune Powerhouse - Our L-lysine chews fortify your cat's immune system, ideal for navigating stress, boarding, illness, or bustling multi-cat homes.

Quick Relief - Combats the severity and duration of feline herpes virus symptoms, such as sneezing, runny nose, eye discharge, conjunctivitis, and other respiratory issues

Essential Support - L-lysine aids in antibody, hormone, enzyme, and vitamin production, enhancing immune defenses and vitality for cats of every age, from playful kittens to wise seniors.

60 Star Shaped Chews - Only the best for your cat. Our Cat L-lysine Chews are made with only natural ingredients and have a salmon flavor that cats love!

Vet-Strength - Formulated with care (and love) by our team of veterinarians, our calming cat chews are safe and effective! Made in the USA using only the worlds best ingredients. 


Guaranteed Analysis per Chew (1.5 g)

Minimum unless stated otherwise.

Crude Protein (min)………….23.0%

Crude Fat (min)…………………7.0%

Crude Fiber (max)…………….1.5%

Moisture (max)………………….11.5%

L-Lysine…………………………….125.0 mg

Calorie Content (calculated)

ME 3,300 kcal/kg        5.0 kcal/chew (1.5g)

Ingredients: Chicken Meal, Chicken Liver,  Glycerin, Cane Molasses,  L-Lysine Hydrochloride, Potato Flour, Salmon Oil, Powder Sugar, Corn Starch, Lecithin, Salt, Phosphoric Acid, Potassium Sorbate (preservative) Methylparaben (preservative), Mixed Tocopherols (preservative) and Propylparaben (preservative).


Cats up to 15 Lb.……………….2 Chews daily

Cats Over 15 Lbs.……………….4 chews daily

Shipping and return details

Free Shipping (arrives in 5-8 business days)
All orders are eligible for free shipping! Please note that we only ship to addresses in the lower 48 of United States. We do not ship internationally or to AK/HI at this time.

Expedited Shipping (arrives in 2-3 business days)
Flat rate of $19.99 USD. Orders placed before 3pm EST Monday - Friday (non holidays) ship the same day. In-stock items are normally shipped within 1-2 business days. Expedited and overnight shipping options are not available to Hawaii, Alaska and PO Boxes. We do not ship on holidays.

Hastle-free Returns
We are happy to accept returns of unopened, unexpired products purchased directly from our website within 30 days of purchase. Please note, we DO NOT accept returns of opened or expired products. We also do not accept returns of items purchased from Amazon or other retailers.

Please send your returns using the carrier of your choice to:

Under the Weather Pet (ATTN: Returns)
1360 Marshall Avenue Williston, VT 05495

Please ensure to include your name and order number.

Once your return has been processed, it may take 3 - 10 days for the refund to be posted to your account.
View full details

Frequently Asked Questions

What does L-lysine do for cats?

L-Lysine supports a cat's immune system, helps manage symptoms of feline herpes virus, promotes collagen production for healthy skin and tissues, aids in nutrient absorption, and contributes to overall feline well-being and vitality

What happens if I give my cat too much L-lysine?

Adverse effects are rare. Like any supplement your cat may experience an upset stomach if they accidentally ingest a large amount of L-lysine.

Should my Cat have L-lysine Chews every day?

Yes - Consistent daily intake can help maintain strong immunity in cats! The frequency of L-Lysine supplementation for cats should be determined by a veterinarian based on the cat's individual health needs and any specific conditions they may have, such as feline herpes virus (FHV-1) or immune system issues.
  • Veterinarian Formulated

    Every product we manufacture has been developed in close collaboration with verterinarians - that means they’re safe, and they work!

  • Manufactured in the USA

    All of our products are manufactured right here in Vermont, USA, always using the highest quality ingredients.

  • Fast and Free Shipping

    Your hands are already full taking care of your furry friend. Save the trips to the store with our fast and free shipping!

Meet Some Of Our Happy Pets