Pets can often let you know how they’re feeling, but it can be hard to tell when they’re sick. Their illnesses can seem so vague and amorphous—a little puking here, some weird lethargy there—and it can be hard to tell the difference between a little under the weather and the start of a serious problem.
Of course, there’s always the vet to help you figure out what’s going on. Sometimes, the answer is surprising:
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When this Twitter user noticed that both her cat and dog had been acting strange, she took them to the vet and discovered that they were being made ill by the essential oils in her diffuser.
When I saw this tweet, I had to wonder—was my cat’s recent puking caused by my own essential oil diffuser? I’d been running it occasionally with lavender and pine oils. I never would’ve put those oils on my cat’s body or in her water, but I hadn’t thought to check if she could be harmed by the oils in the air.
The ASPCA has a robust animal poison control info center and hotline, and their advice on essential oils is sweeping:
Cats are especially sensitive to essential oils, and effects such as gastrointestinal upset, central nervous system depression and even liver damage could occur if ingested in significant quantities. Inhalation of the oils could lead to aspiration pneumonia. There are significant variations in toxicity among specific oils. Based on this, we would not recommend using essential oils in areas where your pets have access, unless pets are supervised or the use of the oil is approved by your veterinarian.
What kind of exposure is dangerous?
I reached out to Dr. Tina Wismer, medical director of the ASPCA Animal Poison Control Center, for more information.
Wismer says that, unless pets have respiratory issues, skin exposure is more dangerous than inhalation. She points out that pets can absorb topically applied oils through their skin, or ingest them orally when they groom themselves. While there are some products made for pets, like flea control products, that contain essential oils, those are low concentrations that are safe for pets. But you should still only use those products as directed. “Cats are particularly sensitive to a lot of toxins because they have fewer metabolizing enzymes in their liver compared to dogs,” Wismer explains. So don’t use a dog product on your cat.
However, diffusing essential oils can still be dangerous to pets. “The most common symptoms for cats and dogs exposed to diffused essential oils are drooling, vomiting, coughing, and sneezing. Diffusing oils can be fatal to cats and dogs that have asthma or other respiratory issues,” Wiser notes.
Which oils are the worst?
According to Wismer, any essential oil could be harmful to pets, depending on how much they’re exposed to and how. But the especially toxic oils, where pets are concerned, include wintergreen, d-limonene (citrus), pine, cinnamon, pennyroyal, eucalyptus, and tea tree. You can still have a diffuser in your home, but Wismer suggests keeping your pet and your running oil diffuser in separate rooms and avoid using the device for long periods of time.
Better safe than sorry. I like my diffuser, but not as much as I love my cat—especially when she’s not puking.
This story was originally published in 2018 and was updated on January 28, 2021 to meet Lifehacker style guidelines.