Lysine for Cats – Where to Buy Lysine Powder and Treats?

lysine for cats

Is your kitty getting all the nutrients she needs to avoid disease and maintain optimal health? Is Lysine for cats necessary?

Clearly, the answer depends a lot on the quality and type of food you're giving her. It also depends on your kitty's specific needs for her body, health, age, and lifestyle.

Truthfully, there are so many factors that go into determining the best diet for your feline family members that it can be hard to make sense of it all sometimes, right?

Now, in a perfect world, both humans and felines would get all the nutrients they need from the foods they eat. But these days—with long-distance transportation, soil quality, environmental toxins, and other things affecting our food—it's not always possible.

This is why supplementation is so essential for a lot of kitties (let alone their human parents).

Want to know one important supplement that your kitty may need? It's called lysine, and it could be the “cat's meow” when it comes to her health.


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Lysine for Cats - Where to Buy Lysine Powder and Treats? 1

You love what you see? Purrfect! Rest assured that I put these products on the list specifically due to their genuine quality and not for other reasons. I would just like to be transparent with you and inform you that FelineLiving may obtain a share of sales or other monetary compensation from the links on this page. I hope your furry friends will love these reviewed products and that it will spark joy in each pair of feline eyes!

Mary Nielsen ♥

Recommended Lysine for Cats 

Lysine for Cats - Where to Buy Lysine Powder and Treats? 2
Viralys Oral Powder for Cats
  • Daily L-Lysine supplement for cats
  • Helps support a strong immune system and eye & respiratory health
  • Highly-palatable fish and poultry flavor
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NOW Pet Health, L-Lysine Powder for Cats
  • Developed to easily provide L-Lysine to your feline companion
  • Veterinarian recommended to support your four-legged friend
  • Supports respiratory and ocular health
Lysine for Cats - Where to Buy Lysine Powder and Treats? 4
VetriScience Vetri-Lysine Plus Chews
  • Tasty chicken-flavored bite-sized chew
  • Recommended by veterinarians
  • Advanced formula supports respiratory and immune systems
Lysine for Cats - Where to Buy Lysine Powder and Treats? 5
Strawfield Pets L-Lysine Immune Support
  • Natural chicken liver flavored powder
  • Designed to boost the overall health of your cat
  • Treats cough, sneezing, runny nose, congestion and colds
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Lysine Supplements for Cats—Our Top Picks

  1. Viralys Oral Powder for Cats
  2. NOW Pet Health, L-Lysine Powder for Cats
  3. VetriScience Vetri-Lysine Plus Chews
  4. Strawfield Pets L-Lysine Immune Support

If you've ever tried buying supplements for yourself, then you know how much of a headache this can be. It's hard to know which supplements are high quality and effective for human consumption…let alone kitty consumption!

We're here to help you out. The following products are our top picks for lysine powder and lysine treats for your cute companions.

As we do with all our reviews, we include in our research customer reviews, price, quality, and overall effectiveness in determining which products make the cut.

1. Viralys Oral Powder for Cats

lysine for cats

Viralys oral powder has been traditionally used for treatment and management of the feline form of herpes virus. As we've mentioned, there's some conflicting data out there on whether lysine is a good nutritional supplement for cats with herpes virus.

But this product is still high quality and provides a good source of lysine if your animal needs it for an immune boost or other reason.

Lysine for Cats - Where to Buy Lysine Powder and Treats? 7
This oral powder has been traditionally used to treat and manage feline herpes and upper respiratory disease. Simply sprinkle over food.


  • Vet-approved
  • Easy to mix into wet or dry cat food


  • Not all cats like the taste
  • Expensive

2. NOW Pet Health, L-Lysine Powder for Cats

Lysine for Cats - Where to Buy Lysine Powder and Treats? 8

For a potent source of dietary lysine that is easy to blend into wet or dry cat food, this powder from NOW could be exactly what you're looking for. It comes form a reputable brand that is family-owned and operated that has earned certification National Animal Supplement Council (NASC) for quality.

Plus, the only ingredient is lysine, with a solid 276 mg per serving. No fillers or additives whatosever.

Lysine for Cats - Where to Buy Lysine Powder and Treats? 9
Provides an immediate source of L-lysine that is easy to blend into wet or dry cat food. It greatly boosts visual and respiratory health systems.


  • Trusted and NASC-certified product
  • Dissolves well in wet food
  • Contains only lysine


  • Expensive
  • May cause allergic reaction in some cats

3. VetriScience Vetri-Lysine Plus Chews

Lysine for Cats - Where to Buy Lysine Powder and Treats? 10

VetriScience Laboratories have created a delicious and nutritious snack for kitties needing a lysine-boost. These chews feature an appealing chicken flavor that most cats seem to enjoy.

Just be sure to close the package's seal well to keep the treats from drying out—which some reviewers say tends to happen regardless.

Lysine for Cats - Where to Buy Lysine Powder and Treats? 11
Features a delicious and nutritious snack for felines needing a lysine-boost. These chews comes in a savory chicken flavor that most cats seem to love.


  • Kitties like the flavor
  • Formulated and manufactured in the US
  • Easy to add to a cat's diet intermittently during times of heightened stress.


  • Contains some undesirable additives like soy lecithin
  • Vegetable oil, and maltrodextrin, not truly “bite-sized” for some cats (but easy to break up into smaller pieces), can dry out.

4. Strawfield Pets L-Lysine Immune Support Cat Supplement

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This powder supplement from Strawfield contain high quality lysine, and is designed to help with feline herpes, immune system function and overall health.

It also treats cough, sneezing, runny nose, congestion and colds in adult and senior cats as well as upper respiratory infections as well as prevents eye infections in kittens.

This product comes in a natural chicken liver flavor which makes it ideal for kittens, adults and senior cats of all breeds.

Lysine for Cats - Where to Buy Lysine Powder and Treats? 13
This supplement is designed to aid with feline herpes, treat upper respiratory infections and boost immune system. It treats runny nose, congestion, cough, sneezing and colds in adult and senior kitties.


  • Contains a good dose of lysine
  • Made in USA
  • Picky eaters like it


  • Some reviewers have expressed concerns over its grainy texture
  • May have to buy more frequently due to dosage/servings.

What is Lysine Exactly?

Lysine for Cats - Where to Buy Lysine Powder and Treats? 14

You've probably heard amino acids referred to as “the building blocks” of protein, which is exactly right. Lysine is a specific type of amino acid found in all cats—and humans, for that matter! It's a major player in a ton of different physiological functions, which we'll talk about in a minute.

Unlike other types of amino acids, lysine is considered an “essential” amino acid because feline and human bodies cannot make it on their own. This means lysine has to be sourced through food.

However, some kitties don't have enough of this important amino acid. This can put their body at risk and make it harder for them to ward off infection, illness, and disease. For this reason, lysine is often given as a feline supplement.

By the way, don't get confused if you see the term L-lysine Hydrochloride or simply L-lysine. These are alternative names for lysine, and they all refer to the same essential amino acid.

Portrait of misunderstanding British Shorthaired Cat

What Does It do for Cats?

As mentioned, lysine does a lot of important things for feline health and wellness.

One of the main roles of lysine in a cat's body is to create enzymes, antibodies, and other compounds that support a healthy immune system. Lysine is also needed to keep a kitty's skin and coat healthy as well as maintain eye function.

This amino acid also helps keep feline bones strong by optimizing calcium absorption, which is an important mineral for bone density.

Does It Help with Feline Herpes Virus?

Proponents of lysine have claimed that this amino acid supplement can help kitties dealing with a chronic (and common) viral infection known as feline herpes.

Signs and symptoms of feline herpes virus can flare up from time to time, especially during times of stress, such as vet visits or house guests. These may include:

  • Cold sores, also called fever blisters (these are typically found on or around the mouth and throat)
  • Sneezing, congestion, sinus discharge/runny noses, wheezing, and other signs of upper respiratory infections
  • Conjunctivitis, which presents as red, irritated, dry, itchy eyes that may also have a cloudy or watery discharge (your kitty may frequently squint or paw at her face)
  • Increased panting
  • Lethargy

Now, the use of lysine for managing feline herpes viral infections has come under some scrutiny recently, and the supplement isn't without its critics.

In fact, a 2015 systematic review published in a veterinary medicine journal found no evidence to support the idea that lysine supplementation effectively prevents or treats feline herpes.

The authors of this review found that some studies actually show lysine supplementation may increase the rate and severity of feline herpes infection.

They also suggest that in some cases lysine supplementation may lower the levels of another essential amino acid called arginine, which could lead to a serious metabolic disturbance called hyperammonemia.


This information has led a lot of vets to change their stance. Many vets no longer advise lysine supplements for herpes and instead focus treatment on antiviral medications, antibiotic medications for secondary bacterial infections, stress reduction, and a high quality diet to support feline immune health.

What's our takeaway?

A lot of pet owners still find that lysine supplements help their kitties manage their herpes symptoms, and some vets may still recommend it. If your cat has feline herpes virus or another chronic health condition, it's best to speak with your vet before adding any new supplements to her diet—and feel free to ask him or her about their understanding about the conflicting research!

In fact, it's best to consult with a vet before making any changes to your cat's diet, whether she's chronically ill or not. If your veterinarian determines that lysine is a supplement for her, he or she can help you determine the correct and safe dosage.

This can give you the peace of mind that you're making the most well-informed decisions possible and adequately supporting your furball's health while minimizing the risk of adverse effects.

Iams Cat Food Review

Where can you buy it?

Now that we know a bit more about lysine benefits and risks, it's time to talk about where you can purchase it if you and your vet decide it's right for your animal.

As a supplement, lysine is actually fairly easy to add into your kitty's nutrition plan. You can find it in many forms—liquid, pill, powder, or even as a chewable treat.

By the way, lysine is also found naturally in foods like beef, fish, eggs, and cheese. If you check your cat food ingredients label, you might see some of these foods listed. That's great, because it means she's already getting at least some of the lysine she needs through her food.

To hedge your bets though, it still may be a good idea to add a lysine supplement—some pet owners think of it as an extra “insurance policy” for their kitty's well-being.

This supplement can be purchased over the counter, so you don't necessarily need a prescription from your vet. As mentioned though, it's still wise to consult with the kitty doc before adding it in. 


All animals (and humans, for that matter) need amino acids in their bodies to support overall health. But because of things like age, illness, diet, and lifestyle, certain kitties don't make or get enough of the right kind of amino acids—including lysine.

Fortunately, there are some wonderful lysine supplements which may help your kitty feel and function better. If you're curious, show this list to your vet to get some feedback before making a purchase, and be sure to check out our other comprehensive reviews for guidance on other kitty products.

What is lysine good for?

Lysine is an amino acid (building block of protein). People use it to make medicine. Lysine is used for preventing and treating cold sores (caused by the virus called herpes simplex labialis). It is taken by mouth or applied directly to the skin.

How much lysine can I give my cat?

Typically, it is recommended for cats to have 400-500mg of lysine each day, especially when trying to treat ailments. Most cat owners have noticed that their cat has a better experience with it if they split it up into two separate 250mg doses each day.

What are lysine treats for cats?

L-Lysine from Pet Natural's comes in a delicious chicken liver bite sized chew that cats love! Lysine is recommended for cats that need added immune support, respiratory health support and for other conditions that are responsive to lysine. L-Lysine from Pet Naturals contains no wheat, corn or artificial ingredients.

Is lysine effective for cats?

For both people and cats, L-lysine is a way to manage and control herpes effectively. This amino acid is present in every cat's body, but some cats do not have enough of it to ward off infections and illnesses.

  • Updated September 12, 2023
Sara Beth Ochoa

Having earned her Doctorate in Veterinary Medicine from St. George University with outstanding academic achievements, Dr. Ochoa boasts exceptional qualifications as a veterinarian. For over seven years, she has been dedicatedly serving at Whitehouse Veterinary Hospital in Whitehouse, TX, where she delivers top-notch care to a diverse range of animals. Furthermore, her educational journey began with undergraduate studies at Louisiana Tech, and she further honed her clinical skills at LSU following her graduation from veterinary school.