Do You See Cats with Runny Eyes?


I am not a veterinarian, this is information that is widely available. Upper respiratory infections (common kitty cold, Feline Herpes Virus) are the most common ailment that affects cats and kittens. Often (not always) upper respiratory symptoms in community cats such as watery eyes, sneezing, wheezing and runny noses are a result of the Feline Herpes Virus (although environmental allergies are a big issue here as well). Most cats have been exposed to the Feline Herpes Virus within the first few weeks of life. Since they are not vaccinated until at least 8 weeks old, many times it is too late for vaccination to prevent infection with it.  

If you notice cats experiencing clear to reddish-brown (not bloody) eye discharge, runny or a clogged up nose, you can begin treatment with L-lysine IMMEDIATELY.  This supplement could greatly improve the situation in outdoor cat colonies or individual outdoor cats that have these symptoms (or any cat for that matter). L-lysine has the potential to lessen and possibly eliminate signs of Feline Herpes Virus infection. L-lysine, an essential Amino Acid, halts the replication of the virus. It is perfectly safe to give to cats and even yourself (for other issues obviously).  Always watch for diarrhea when giving to kittens.  This supplement does not always work for all cats and cannot always completely stop the upper respiratory symptoms, BUT we continue to have and see others have great success with it. Remember to ALWAYS consult a veterinarian when a cat's symptoms do not improve after one week. *** If you see green or yellow discharge, or the cat stops eating then the cat NEEDS TO SEE A VET ASAP! Santa Cruz Veterinary Clinic provides medical care for community cats in Tucson/Pima County under their community cat program.***

For cats SHOWING SYMPTOMS(watery eyes/nose): Kittens – 250 mg twice per day for 5 days (watch for diarrhea, consider working up to this dose); Adults – 500 mg twice per day for 5 days.  Maintenance for cats NOT showing symptoms anymore: 250 - 500 mg once per day. Cats may remain on L-lysine indefinitely as it helps boost their immune system. 

Just SPRINKLE THE POWDER ON THEIR FOOD. If you want to give the L-lysine to just one or two sick cats then you can put their needed dosage in a food bowl just for them. If there are many cats that need it or you cannot separate the ones that need it from the other cats, then you will need to multiply the # of cats you are feeding by the amount of L-lysine needed and add it to the community food bowls.  
example: ( # of cats ) x ( 500 mg) = mg needed per feeding 5 cats x 500 mg = 2,500mg

Symptoms should significantly lessen. If they do not lessen, community cats may be taken to Santa Cruz Veterinary Clinic for medical care under their community cat program.
POWDERED L-lysine is the easiest to use and usually the least expensive but can no longer be found locally at a reasonable price ($10 or less) or at all because of the COVID-19 Pandemic. Powdered l-Lysine has been back ordered at many stores.  The following are the least expensive sources of powdered L-lysine online (Prices were accurate as of 5/21/2020):

Now Pets L-Lysine For Cats Powder, 8 oz container is made for cats so the other ingredients in it, such as flavoring, are safe to give. It can be sourced at and for $7.67

Tomlyn Immune Support L-Lysine Powder Cat Supplement, 3.5-oz tub is made for cats so the other ingredients in it, such as flavoring, are safe to give.  It can be sourced at, and for $12.99.

*There are other brands of L-lysine powder marketed specifically for cats, with the exact same active ingredient, but cost twice as much. 

Best Naturals L-Lysine Premium Formula Pure Powder is available at for $10.99.  This is pure lysine, with no additives.  It is unflavored but that generally doesn't stop cats from eating it. Click on photo for product page. 1/4 teaspoon of this product is 550mg and 1/8 teaspoon is 275mg.  Recommended dosages are listed below as 500mg and 250mg so use slightly less than 1/4 or 1/8 teaspoon. 

500mg or 250mg capsules unflavored (again, cats will generally eat this without added flavor) are still available locally and can be opened and then sprinkled into/onto food.  500mg or 200mg unflavored tablets are also still available locally and can be crushed well with the back of a spoon and then sprinkled into/onto food. You can find this, generally under $10 for 100-200 count at Walmart and Sprouts.  They all contain magnesium stearate in them which can potentially be problematic. CAUTION Occasionally L-lysine supplements contain the preservative "propylene glycol" which is dangerous for cats. Cats who have ingested propylene glycol have been shown to experience side effects such as blood reactions. Always choose a brand of L-lysine supplement either marketed for cats or without added ingredients. The brand we mentioned above does NOT contain anything other than "pure L-lysine."

*PLEASE NOTE: the “Nature's Life” powdered L-Lysine which we used to recommend is no longer available at Sprouts in Tucson