Lysine is an essential amino acid, often described as one of the building blocks for protein. It can boost immune support, improve calcium retention, and even aid in the fight against feline herpes and conjunctivitis.
But, cat supplementation is a somewhat complicated and challenging field. In an ideal world, your cat will get all of its vitamin and mineral requirements from its food, but not all foods are as nutritionally complete as you might believe. There are many supplement choices out there, including lysine supplements, and they can take the form of powders, liquids, chews, tablets, and more.
Below, you will find reviews of ten of the best lysine supplements for cats, including different types of supplements and in various quantities. You will also find a guide on lysine, its role in your cat’s health and wellbeing, and how to choose the best supplement for your feline friend.
A Glance at Our 2023 Favorites
Image Product Details
Best Overall
PetHonesty Lysine Cat Supplement
Contains omega fatty acids and quercetin
Suitable for kittens, adults, and senior cats
Powder supplements can be added to food or treats
Check Price
Best Value
NOW Pets L-Lysine Supplement
Cheap
Nothing but lysine
One jar goes a long way
Check Price
Premium Choice
Thomas Labs Felo Lysine Powder
100% lysine
Includes a scoop
Powder can be spread on your cat’s food
Check Price
Best for Kittens
VetriScience Vetri-Lysine Cat Chews
Chicken liver flavored
Two months’ kitten supply in one bottle
No scooping, measuring, and hiding powder
Check Price
Strawfield Pets L-Lysine Supplement
A jar lasts six months
Mixes well with wet food
100% Lysine supplement
Check Price
The 10 Best Lysine Supplements For Cats
Supplements come in liquid, tablet, and powder form. While tablets and chews are convenient for those cats that willingly take anything with a chickeny aroma, they can be difficult to get down all pets. And many cats will refuse liquids, leaving you to syringe it into their mouths and prevent them from spitting it out.
Supplement type: Powder
Volume/Quantity: 4.2oz
Life stage: All
Check Price on Chewy
PetHonesty Lysine Immune Health+ Tuna & Chicken Flavored Powder Immune Supplement For Cats comes as a flavored powder. It can be mixed with food or put on your cat’s favorite treats to make it more palatable, and because it has a tuna and chicken flavor, it shouldn’t detract from the overall flavor.
You should always avoid putting supplements or other additives in cat water: water should be fresh and available 24 hours a day. If your cat doesn’t like the flavor of the supplement, it can put them off drinking from the bowl in future, too.
The PetHonesty powder also contains omega fatty acids and quercetin, a combination that is designed for immune support and can be especially beneficial for allergic cats and during wintertime when cold symptoms tend to persist.
The powder is quite expensive and you do need to measure scoops and add it to food or treats yourself, but it is suitable for cats of all ages, is suitable for picky cats because it can be added to a treat of their choice, and contains a good mixture of immune support ingredients so is our choice as the best overall lysine supplements for cats.
Pros
Powder supplements can be added to food or treats
Suitable for kittens, adults, and senior cats
Contains omega fatty acids and quercetin
Cons
Not as convenient as a chew or tablet
Quite an expensive tub
NOW Pets L-Lysine Immune System Support Cat Supplement is another lysine powder supplement. This lacks the flavoring and the additional ingredients of the PetHonesty powder and is made from nothing but L-Lysine Hydrochloride. This means that your cat is getting more of the lysine you supplement with every powder, but attentive cats might pick up on the flavor in their food.
Powder supplements can be added to food or treats
Suitable for kittens, adults, and senior cats
Contains omega fatty acids and quercetin
- Powder supplements can be added to food or treats
- Suitable for kittens, adults, and senior cats
- Contains omega fatty acids and quercetin
Not as convenient as a chew or tablet
Quite an expensive tub
- Not as convenient as a chew or tablet
- Quite an expensive tub
Supplement type: Powder
Volume/Quantity: 8oz
Life stage: All
Because it lacks some of the additional ingredients, however, this powder costs a lot less per ounce and you feed less of it, so it works out cheaper than most other supplements: its lysine only formula and low cost ensure it is the best lysine supplement for cats, for the money.
Despite being described as a powder, it is more granular so is easier for cats to spot (and ignore) on food, and its lack of flavoring means that it won’t be suitable for particularly picky felines.
Pros
Cheap
One jar goes a long way
Nothing but lysine
Cons
Unflavored so easier to detect
Granular, rather than powder
Thomas Labs Felo Lysine Powder Cat Supplement is an unflavored powder supplement that is 100% lysine. It has no extra ingredients and contains no flavorings. The jar is very large and, although the required amount is more than with some other powders, it should last a long time in a single cat household. The jar does include a scoop, which isn’t always the case, but it is expensive.
Cheap
One jar goes a long way
Nothing but lysine
- Cheap
- One jar goes a long way
- Nothing but lysine
Unflavored so easier to detect
Granular, rather than powder
- Unflavored so easier to detect
- Granular, rather than powder
Supplement type: Powder
Volume/Quantity: 35oz
Life stage: All
While some powders only require a fraction of a teaspoon, this one requires a whole teaspoon for adult cats. It is unflavored, too, and a teaspoon of dry powder on top of a sachet of food is easily recognized by astute cats so it can lead to you having to feed more food, and it is difficult to combine with a treat. The amount you have to feed, combined with the price, also means that it works out as an expensive choice of lysine powder supplement.
Pros
100% lysine
Powder can be spread on your cat’s food
Includes a scoop
Cons
Expensive
Dosing recommendations require a lot of powder
Some cats are especially sensitive to alien flavors and unusual textures in their food, but will gladly take some tasty chicken flavored chews. This can be especially true in kittens that are fed smaller portion sizes. The smaller amount of food struggles to take on a powder supplement without changing its flavor.
100% lysine
Powder can be spread on your cat’s food
Includes a scoop
- 100% lysine
- Powder can be spread on your cat’s food
- Includes a scoop
Expensive
Dosing recommendations require a lot of powder
- Expensive
- Dosing recommendations require a lot of powder
Supplement type: Soft chews
Volume/Quantity: 120
Life stage: All
VetriScience Vetri-Lysine Plus Chicken Liver Flavored Soft Chews Immune Supplement For Cats are chicken liver flavored, which tends to be a popular choice with most cats. As well as being palatable, they are easy to chew and digest, and the pack includes 120 soft chew tablets. At the recommended dosing guideline of two chews per day for kittens, a single bottle will last approximately two months so the bottle is reasonably priced.
There is a long list of ingredients in these chews, and if your cat doesn’t like a soft chew they can be difficult to crush up and add to food so it is more likely that you will be left with an open, unusable bag of chews.
Pros
Chicken liver flavored
No scooping, measuring, and hiding powder
Two months’ kitten supply in one bottle
Cons
Not all kittens will take, or even try, soft chews
Difficult to crush up or otherwise administer
Strawfield Pets L-Lysine Immune Support Cat Supplement is a generous jar of 100% L-Lysine Hydrochloride supplement powder. It includes a scoop for measuring and dosing and using that scoop, the jar contains enough powder for 200 portions which, when fed daily, will last more than 6 months in a single cat household. It is suitable for kittens, as well as adult cats, and is a good supplement for immune system support.
Chicken liver flavored
No scooping, measuring, and hiding powder
Two months’ kitten supply in one bottle
- Chicken liver flavored
- No scooping, measuring, and hiding powder
- Two months’ kitten supply in one bottle
Not all kittens will take, or even try, soft chews
Difficult to crush up or otherwise administer
- Not all kittens will take, or even try, soft chews
- Difficult to crush up or otherwise administer
Supplement type: Powder
Volume/Quantity: 7oz
Life stage: All
This, like other 100% Lysine powder supplements, can be especially beneficial to cats with environmental and seasonal allergies because it does not contain any grains or other potential allergens and irritants. It also boosts the immune system so it can help alleviate symptoms like coughing and sneezing.
Although the jar is quite expensive, it does go a long way and it mixes well with wet food. However, it does have quite a strong aroma which can be easily detected and may put some cats off readily eating their topped food.
Pros
A jar lasts six months
100% Lysine supplement
Mixes well with wet food
Cons
Strong smell
Some cats won’t like the lysine flavor
Lysine is known to help prevent or reduce feline herpes flare-ups and is also beneficial for good eye health. In fact, vets have long administered L-Lysine to cats with the Herpes virus, to help treat the condition. Vets recommend that cats get 500mg of lysine per day and each Optixcare L-Lysine Cat Chew contains that required 500mg.
A jar lasts six months
100% Lysine supplement
Mixes well with wet food
- A jar lasts six months
- 100% Lysine supplement
- Mixes well with wet food
Strong smell
Some cats won’t like the lysine flavor
- Strong smell
- Some cats won’t like the lysine flavor
Supplement type: Soft chews
Volume/Quantity: 60
Life stage: All
This means that you should only need to give your cat one of the chews a day, although Optixcare advises a dose of one or two chews per day, as required. A single tub, which is moderately priced, will last between one and two months.
The chews do include chicken flavor to make them more appealing to the feline palate, but there will always be some cats that turn their noses up at a flavor, no matter how appealing. They do work out more expensive than some of the powders and the cube-shaped chews are quite large, so they may need cutting or breaking up, especially if you are giving to a small cat or kitten.
Pros
Chicken-flavored soft chews
Contain the recommended 500mg of lysine, per chew
Cons
Quite large
Work out more expensive than powder
Duralactin Feline L-Lysine Cat Supplement combines the benefits of L-Lysine with Microlactin. Microlactin is a type of milk that is rich in antibodies and has proven effective against conditions like arthritis. It is also believed to support the immune system, making it a beneficial addition to this supplement.
Chicken-flavored soft chews
Contain the recommended 500mg of lysine, per chew
- Chicken-flavored soft chews
- Contain the recommended 500mg of lysine, per chew
Quite large
Work out more expensive than powder
- Quite large
- Work out more expensive than powder
Supplement type: Liquid
Volume/Quantity: 32.5ml
Life stage: All
Duralactin Feline L-Lysine Cat Supplement is a liquid supplement that comes in a 32.5ml syringe and is usually given during flare-ups of chronic pain caused by osteoarthritis. A single dose is 2.5ml for adults and 1.25ml for kittens.
Dosing can be challenging because you have to judge according to the notches and lines on the syringe. This is especially true for kitten doses because you need to judge halfway between two measures. However, the syringe does contain enough supplement for between two and four weeks of constant use. It can be difficult to store, in the syringe, if you don’t need to administer the whole thing in one period.
Pros
Includes Microlactin
Used to fight chronic pain flare-ups and boost immune system
Reasonable price
Cons
Can be difficult to dose accurately
Difficult to store appropriately
- 21st Century L-Lysine Amino Acid Support Cat Supplement Chew
Check Latest Price
Supplement type: Soft chews
Volume/Quantity: 100
Life stage: Adult, Senior
21st Century Essential Pet L-Lysine Amino Acid Support Soft Chews contain L-Lysine Hydrochloride as well as a host of flavors and binding agents, including brewers dried yeast, which can act as an allergen in some cats. Canola oil, which is a somewhat contentious ingredient in cat foods and treats, is in the list of ingredients, although the small amount in each chew and the minimal intake of your cat means that it should be safe in these levels, and is considered safe by a lot of experts, anyway.
Includes Microlactin
Used to fight chronic pain flare-ups and boost immune system
Reasonable price
- Includes Microlactin
- Used to fight chronic pain flare-ups and boost immune system
- Reasonable price
Can be difficult to dose accurately
Difficult to store appropriately
- Can be difficult to dose accurately
- Difficult to store appropriately
Check Latest Price
Supplement type: Soft chews
Volume/Quantity: 100
Life stage: Adult, Senior
Although flavored, the chews have not proven popular with all cats, but they are reasonably sized and can be broken up into wet food to disguise them from most cunning felines. The price is reasonable and a bottle contains enough supply for three months at the recommended levels. 21st Century advises feeding one tablet per 10 pounds of cat weight, which means that the average cat will need one chew per day.
Pros
Good price
Soft chews
Cons
Contains some contentious ingredients, albeit in small quantities
Not a popular flavor with a lot of cats
Cat supplements can take many forms and even the most difficult cats can be persuaded to take one form or another. If you struggle with powder and chews, Vetoquinol Enisyl-F Paste Immune Supplement For Cats is another alternative.
Good price
Soft chews
- Good price
- Soft chews
Contains some contentious ingredients, albeit in small quantities
Not a popular flavor with a lot of cats
- Contains some contentious ingredients, albeit in small quantities
- Not a popular flavor with a lot of cats
Supplement type: Paste
Volume/Quantity: 100ml
Life stage: All
The paste gel can, according to Vetoquinol, be given directly into the mouth by rubbing it on their gums, while the tuna flavor means that some cats will lick it straight from your finger. Other suggestions include putting it on their paws so that they naturally lick it off, or mixing it in with wet food to disguise it. Rubbing it on the paws is messy and a powder tends to be a cheaper method for mixing this supplement into food.
The tub does include a pump, which delivers 1ml of the gel and it is advised that you give two pumps, twice daily.
If you struggle to get your cat to accept the gel, it will be very difficult to do so twice a day, and the dosing means that this expensive tub will last less than a month before it needs replacing.
Pros
Includes a handy dispensing pump
Tuna flavored
Paste might be suitable for some chew-hating cats
Cons
Expensive
Requires a lot of regular administration
Messy when applied to paws
Pet Naturals L-Lysine Cat Chews are chicken liver flavored cat chews that are naturally formulated and deliver 250mg of lysine per chew. This does mean that you need to feed one or two chews per day, according to requirements, but the pack is inexpensive and contains enough of the chicken liver flavored chews to last between one and two months.
Includes a handy dispensing pump
Tuna flavored
Paste might be suitable for some chew-hating cats
- Includes a handy dispensing pump
- Tuna flavored
- Paste might be suitable for some chew-hating cats
Expensive
Requires a lot of regular administration
Messy when applied to paws
- Expensive
- Requires a lot of regular administration
- Messy when applied to paws
Although the ingredients are natural, there are several grains and canola oil on the list so owners of cats with allergies and sensitivities may be best avoiding these. Considering they are a soft chew supplement, the tablets are hard and crunchy, which will also put some cats off eating them.
Pros
Cheap
Natural ingredients
Cons
Hard and brittle for soft chews
Contain grains and canola oil
Cheap
Natural ingredients
- Cheap
- Natural ingredients
Hard and brittle for soft chews
Contain grains and canola oil
- Hard and brittle for soft chews
- Contain grains and canola oil
Buyer’s Guide: Selecting The Best Lysine Supplement For Cats
There are many different types and forms of supplement for cats, including L-Lysine. This amino acid is considered especially beneficial for cats that suffer from feline herpesvirus, although it is also used as an immune system booster and to alleviate symptoms of immune disorders like arthritis. The supplement can take the form of a powder, soft chew, liquid, or even a paste gel, and is usually given daily or during any flare-ups of conditions being treated.
What Is Lysine?
Lysine is an amino acid. As with humans, cats are unable to produce lysine themselves and need to get it through diet or, in some cases, supplementation. This essential mineral can be found in some cat foods. Look for Lysine, L-Lysine, L-Lysine Hydrochloride, or L-Lysine Monohydrochloride on the ingredients label. If your cat suffers from feline herpes or you have been advised that it needs more lysine in its diet, you can administer a lysine supplement rather than change food and allow you greater control and precision over the dosing of this mineral.
How Much Lysine Should I Give My Cats?
Vets recommend that cats can safely take 500mg of lysine daily, and at least according to one study that level helped to reduce instances of conjunctivitis caused by FHV-1. Most supplements recommend giving up to 250mg for kittens and 500mg for adult cats and are dosed accordingly. However, you should consider any food-based lysine when working out the amount to give.
Can Cats Take L-Lysine Daily?
L-Lysine is also considered beneficial to boost the immune system and can help with calcium absorption and uptake. Therefore, it is given as a daily supplement and it is considered safe to give to a cat every day.
Supplement Types
Most supplements come in a variety of forms, allowing you to choose the one that your cat tolerates most and that has the desired vitamins, minerals, and other ingredients.
The most commonly found lysine supplements are available as:
Powder – Powder is arguably the easiest supplement to administer. It can be mixed with wet food or dry food, or even combined with a cat treat to mask any flavor, aroma, or texture. It does require a little work measuring the amount of powder but most of the powdered supplements do come with a scoop or they offer dosing guidelines using teaspoon measurements. Some very picky and astute cats might still notice the odd taste and leave their food, while some so-called powders are more granular and difficult to hide even in wet canned food.
Liquid – Liquids are less common than powders and are usually administered via a syringe that the cat owner squirts into the cat’s mouth. Typically sold in a bottle with an accompanying syringe, some companies sell the liquid already in a measured and marked syringe. If you have a fairly tolerant cat, a liquid syringe is quick and convenient but the storage of a half-full syringe is more difficult than the storage of a tub of supplement powder.
Soft chews – If you have the kind of cat that will at least try to eat anything you give it, soft chews could be a good option. These are usually flavored with something like chicken liver or chicken. They have a chewy texture and, if your cat enjoys the flavor, it will be very easy to give them what they deem to be a treat. If your cat won’t eat the soft chew directly, it can be difficult to crush or break them up and add them to wet food.
Treats – Other types of treat include biscuits. Chews and biscuits contain other ingredients as well as lysine. These ingredients may be used for flavoring the chew or as a binding agent to ensure that the supplement remains inside the treat until eaten, but it is worth checking those ingredients. Treats are convenient, as long as your cat accepts them and likes the flavor. Otherwise, they are very difficult to give.
Paste gel – A paste gel has the consistency of a gel and can be fed directly to the cat, rubbed on their gums, or even rubbed on their paws. Rubbing the gel on the paws encourages the cat to lick them clean and therefore take on the lysine ingredient, but this isn’t a reliable or accurate means of administering the supplement and it can leave a sticky mess around the house.
Additional Ingredients
Some supplements combine lysine with other beneficial ingredients. For example, a supplement might contain omega fatty acids or microlactin. These ingredients are usually chosen because they complement the desired effects of the lysine. Microlactin, for example, is an antibody-rich type extract of cow’s milk that aids in the fight against arthritis inflammation and pain.
Powder – Powder is arguably the easiest supplement to administer. It can be mixed with wet food or dry food, or even combined with a cat treat to mask any flavor, aroma, or texture. It does require a little work measuring the amount of powder but most of the powdered supplements do come with a scoop or they offer dosing guidelines using teaspoon measurements. Some very picky and astute cats might still notice the odd taste and leave their food, while some so-called powders are more granular and difficult to hide even in wet canned food.
Liquid – Liquids are less common than powders and are usually administered via a syringe that the cat owner squirts into the cat’s mouth. Typically sold in a bottle with an accompanying syringe, some companies sell the liquid already in a measured and marked syringe. If you have a fairly tolerant cat, a liquid syringe is quick and convenient but the storage of a half-full syringe is more difficult than the storage of a tub of supplement powder.
Soft chews – If you have the kind of cat that will at least try to eat anything you give it, soft chews could be a good option. These are usually flavored with something like chicken liver or chicken. They have a chewy texture and, if your cat enjoys the flavor, it will be very easy to give them what they deem to be a treat. If your cat won’t eat the soft chew directly, it can be difficult to crush or break them up and add them to wet food.
Treats – Other types of treat include biscuits. Chews and biscuits contain other ingredients as well as lysine. These ingredients may be used for flavoring the chew or as a binding agent to ensure that the supplement remains inside the treat until eaten, but it is worth checking those ingredients. Treats are convenient, as long as your cat accepts them and likes the flavor. Otherwise, they are very difficult to give.
Paste gel – A paste gel has the consistency of a gel and can be fed directly to the cat, rubbed on their gums, or even rubbed on their paws. Rubbing the gel on the paws encourages the cat to lick them clean and therefore take on the lysine ingredient, but this isn’t a reliable or accurate means of administering the supplement and it can leave a sticky mess around the house.
- Powder – Powder is arguably the easiest supplement to administer. It can be mixed with wet food or dry food, or even combined with a cat treat to mask any flavor, aroma, or texture. It does require a little work measuring the amount of powder but most of the powdered supplements do come with a scoop or they offer dosing guidelines using teaspoon measurements. Some very picky and astute cats might still notice the odd taste and leave their food, while some so-called powders are more granular and difficult to hide even in wet canned food.
- Liquid – Liquids are less common than powders and are usually administered via a syringe that the cat owner squirts into the cat’s mouth. Typically sold in a bottle with an accompanying syringe, some companies sell the liquid already in a measured and marked syringe. If you have a fairly tolerant cat, a liquid syringe is quick and convenient but the storage of a half-full syringe is more difficult than the storage of a tub of supplement powder.
- Soft chews – If you have the kind of cat that will at least try to eat anything you give it, soft chews could be a good option. These are usually flavored with something like chicken liver or chicken. They have a chewy texture and, if your cat enjoys the flavor, it will be very easy to give them what they deem to be a treat. If your cat won’t eat the soft chew directly, it can be difficult to crush or break them up and add them to wet food.
- Treats – Other types of treat include biscuits. Chews and biscuits contain other ingredients as well as lysine. These ingredients may be used for flavoring the chew or as a binding agent to ensure that the supplement remains inside the treat until eaten, but it is worth checking those ingredients. Treats are convenient, as long as your cat accepts them and likes the flavor. Otherwise, they are very difficult to give.
- Paste gel – A paste gel has the consistency of a gel and can be fed directly to the cat, rubbed on their gums, or even rubbed on their paws. Rubbing the gel on the paws encourages the cat to lick them clean and therefore take on the lysine ingredient, but this isn’t a reliable or accurate means of administering the supplement and it can leave a sticky mess around the house.
Flavorings are common in treats and chews. They make the supplement more palatable and poultry or chicken liver flavor can make it easier to convince a cat to swallow the treat.
If your cat has any sensitivities to ingredients, you should always check the ingredients on the label and ensure that you aren’t feeding something that might exacerbate allergy symptoms and immune system deficiencies.
Conclusion
Lysine is an amino acid that, because cats cannot produce it themselves, is considered an essential amino acid that must be provided through diet or supplementation. It is said to improve the immune system and combat the side effects associated with feline herpes.
With so many different types and styles on the market, we hope that our reviews of the best lysine supplements for cats have helped you find the one that’s right for you and your cat.
PetHonesty Lysine Immune Health+ Tuna & Chicken Flavored Powder is an easy-to-administer powder that is well priced and mild tasting. NOW Pets L-Lysine Immune System Support Cat Supplement is another powder that is even cheaper than PetHonesty’s product but it is more granular which means that it can be a bit trickier to mask in your cat’s food.
Featured Image Credit: Anton27, Shutterstock
