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Is Monstera Toxic to Cats and Dogs?

The genus Monstera provides us with several species and cultivars that are popular houseplants in temperate climes. ASPCA lists it as toxic, so caution is advised for pet owners.

However, it can be argued that ‘toxic’ isn’t really the correct term. The reason this genus is branded as toxic is because all of its parts contain calcium oxalate crystals – more on what those are below.

Calcium oxalate crystals are highly irritating, especially to the mouth and even the stomach when ingested. If your cat or dog takes a bite out of your Monstera (whether it’s a Monstera deliciosa, a Monstera adansonii or one of the other species), it probably won’t have a great time. 

The thing is, although your cat or dog might show signs of pain and irritation after taking a bite out of your Monstera, it should otherwise be fine. The only real danger is if an uncommon swelling reaction occurs. There is no toxin in its system slowly working to shut its body down: just a nasty sensation on the tongue and throat area.

Another thing to remember before panicking or avoiding these houseplants altogether is that many pets will simply leave all your houseplants alone. So if your pets show no inclination to eat your plants, keeping them in the same home won’t necessarily be a massive problem. 

So, Not Toxic. But Is It Dangerous?

Whether you want to call it ‘toxic’ or just ‘irritating’, the real question is of course whether Monstera is dangerous or not. Although I’d personally try to keep this houseplant out of my pet’s reach, there is no real reason to panic if it does get its paws on it.

After the pain from the initial bite, there’s pretty much no way it’ll go for another one, meaning the real danger this plant poses is limited.

Aside from the above, Monstera leaves aren’t really the kind of dangly-stringy sort that cats like, so it’s probably not likely your feline friend will try to take a chomp out of them in the first place. It’s probably more likely to go for your spider plant or string of hearts. Dogs, on the other hand – especially young puppies – may be more at risk. 

Tip: Although the ‘toxic’ label for Monstera and other calcium oxalate-rich houseplants might not be particularly accurate, keep in mind that this doesn’t go for all species that are referred to as such. Some really are highly toxic, like lilies. Always check before you purchase any new plant. 

Calcium Oxalate Crystals

Now that we’ve clarified some things about Monstera toxicity, lhere is a little more information about calcium oxalate crystals:

  • Calcium oxalate crystals are also what causes kidney stones.
  • Calcium oxalate crystals are created inside the plant’s cells and can be needle shaped (called raphids). Sometimes they even have barbs (Franceschi, 2001). No wonder they hurt!
  • It’s not entirely sure if the calcium oxalate in plants is meant to regulate calcium levels, deter herbivores or if it has another function (Franceschi & Horner, 1980).
  • Some popular fruits and vegetables contain calcium oxalate crystals. Spinach in particular has high concentrations.
  • Quite a number of houseplants contain large enough concentrations of calcium oxalate crystals to be irritants. Dieffenbachia is the most well-known culprit and can hurt pretty badly. Syngonium, Philodendron, Alocasia… all these popular plants are on the list.
  • All in all, it’s not pleasant stuff to have touching your mucous membranes. And yep, there have been cases in humans as well (Pang, Ng & Lau, 2010).
  • But is it deadly? No, unless there is prolonged exposure or a reaction that causes excessive swelling, all should be well after treatment.

Will My Pet Be Okay?

If your pet managed to reach your Monstera and take a bite, first off, don’t panic. As we discussed, your furry friend will live. Here’s what you do:

  • Take a look at your pet and the inside of its mouth. Keep an eye out for redness and swelling. If all seems well, you probably don’t have to do anything.
  • Do you see irritation or does your pet appear to be in pain? Offer water or something more enticing to stimulate drinking. This can wash the crystals from the mouth. You can also try rinsing out its mouth yourself.
  • If your pet is still clearly suffering after this, or if you’re worried the swelling might block its airway, head to the vet. They might administer a painkiller and offer additional treatment.

Tip: The above basically applies to kids as well. After having some water or milk, the pain won’t be gone, but things should usually be fine. If you’re really worried, you can always ring a doctor.

Will My Plant Be Okay?

Although it’s pretty clear by now that your Monstera is perfectly capable of defending itself, the sight of a maimed plant can be worrisome.

Your Monstera will usually be absolutely fine. Unfortunately the damaged foliage won’t recover, so you can remove it if you find it unsightly. Other than that, the plant should keep growing as usual.