Is Catnip Bad for Cats With a Heart Murmur?

Dear Most Esteemed and Knowledgeable Kitties:

We love when our human reads Sparkle the Designer Cat. She has learned a lot that has made living with us better. Today Sparkle was talking about ‘nip and it made her think of a question she recently got from a potential adopter she couldn’t answer. Our question is below. Can you help us?

Is ‘nip okay for kittens? and is there a concern about having ‘nip or ‘nip toys around for cats with heart murmurs? We are very concerned our human is going to cut off our supply because Carson is a kitten (10 months) and Mica has a murmur. We are trying to convince her that ‘nip is more like aromatherapy and not recreational drugs for cats.

~ Buddy and the greenleaf caboodle

Siouxsie: Well, first of all, thank you, Sparkle, for sending your friends over here to see if we can answer their question!

Thomas: First of all, before we answer your question, we’ll remind you that we’re not veterinarians, and if you want a real solid answer to any health-related question, the best person to ask is your vet.

Dahlia: That said, we can give you some general information about heart murmurs, which might help your human figure out what to ask the vet.

Thomas with a catnip toy. Photo by JaneA Kelley

Thomas loves, loves, LOVES catnip -- the fresher and more potent, the better. Photo by JaneA Kelley

Siouxsie: Most sources of information about catnip don’t say anything about the herb doing harm to cats with heart murmurs. On the other hand, Dr. Shelby Neely of Ask The Cat Doctor says she doesn’t give catnip to one of her cats because he has hypertrophic cardiomyopathy (or HCM for short), a kind of heart disease.

Thomas: HCM is just one of many conditions that can cause heart murmurs. Sometimes cats have murmurs when they’re kittens and then grow out of them as adults — perhaps because some structure within the heart repairs itself as the kitten develops.

Dahlia: But in order to find out exactly why Mica has a heart murmur, your vet is going to have to do some diagnostic tests including chest X-rays, Doppler studies, and an echocardiogram.

Siouxsie: Heart murmurs are graded on a six-point scale. According to, these are the definitions of the six grades of heart murmur:

  • Grade I — barely audible
  • Grade II — soft, but easily heard with a stethoscope
  • Grade III — intermediate loudness; most murmurs which are related to the mechanics of blood circulation are at least grade III
  • Grade IV — loud murmur that radiates widely, often including opposite side of chest
  • Grade V — very loud, audible with stethoscope barely touching the chest; the vibration is also strong enough to be felt through the animal’s chest wall
  • Grade VI — very loud, audible with stethoscope barely touching the chest; the vibration is also strong enough to be felt through the animal’s chest wall.

Thomas: If Mica’s murmur is very severe or he has serious heart disease, it may not be safe for your human to give him catnip because the stimulant effects could cause bad things to happen.

Dahlia: But it should be OK in moderation, in most cases. We’d definitely recommend that your human talk to your vet and find out what’s causing Mica’s murmur. Then your human should ask the vet whether he or she thinks it’s safe to give him catnip.

Siouxsie: But the good news is, even if your human can’t safely give Mica catnip, there’s no reason she can’t throw a catnip party for the rest of you! All she has to do is keep Mica in a separate room while the ‘nip is out.

Thomas: That’s right. Nobody should keep healthy cats away from their ‘nip!

Dahlia: I wish I was feeling well enough to get out of bed, let alone tipple the ‘nip. *sniffle*

Thomas: Aww, poor little sweetie. I’ll come over there and have a snuggle with you. I’m sorry I hissed at you when you came home from the vet, my poor, sick little baby girl …

Siouxsie: Yuck!

  • Sparkle

    Thanks for answering this question – I knew you guys would be able to dig up some great info and advice!

  • Susan C

    Thomas… I’m sure your hisses were from Dahlia smelling funny… it was difficult for you to tell who she was … since you rely mostly on smell. She probably knew she smelled funny and understood.

  • Deb Robichaud

    This was a really informative article! Loved it! I have a cat who has a heart murmur and was wondering about this question myself.

  • caren gittleman

    My Angel Bobo was diagnosed with hypertrophic cardiomyopathy when he was approx 13 ish…yes obviously that is well past kitten age (duh! lol) but my Vet at the time said that catnip (and believe it or not laser lights, due to the excitement level) were not the best idea for my senior boy.

  • Donna

    Very informative article. I hope you get better soon, Dahlia! Hope it’s just a cold?

  • RomeotheCat

    Great article! I am glad I do not have HCM because Pugsley and I love CATNIP!!