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. 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 vaccine to prevent 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 then the cat NEEDS TO SEE A VET! Call us at 520-256-0443 if you do not know how to get community cats vet care in Pima County. ***
POWDERED L-lysine (not capsules or tablets) can be found at most health food and vitamin stores in town. In Tucson, we have found that it is least expensive at Sprouts ( You can get a 200 gram tub of “Nature's Life” brand L-lysine powder for $9.99 but is frequently on sale for less. We have not found this available any less expensive online so this is a good price.

*There is a brand of L-lysine powder marketed specifically for cats, with the exact same ingredient, but costs twice as much because it is flavored. We have never had problems with any cats eating their food after we sprinkled unflavored L-lysine onto it.

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.
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
 20 cats x 500 mg = 10,000mg = approximately 5.75 teaspoons 

If you only have a few cats then buying the 250 mg or 500 mg powder containing capsules may be easier, but the already powdered L-lysine in a tub is more cost effective. We are happy to do the math for you to figure out how much powder you need to give for the amount of cats you are feeding. Please email us at and we will respond with the amount needed.

*PLEASE NOTE: the “Nature's Life” powdered L-Lysine available at Sprouts in Tucson is 435mg per ¼ teaspoon so: 
 You can use a gram scale to measure out the needed dosage  OR
 You can approximate 500mg by using a tiny bit more than ¼ teaspoon OR
 You can approximate 250 mg by using a bit more than 1/8 teaspoon

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. 

Symptoms should significantly lessen. If they do not lessen, CALL US at 520-256-0443 or email