Eucalyptus oil has been used as an herbal remedy by Australian aboriginals for thousands of years, but it wasn’t introduced to the Western world until discovered by a ship’s surgeon in 1788 (1, 2). It’s recently gained in popularity again. And, where human trends go, our canine friends follow. So, is eucalyptus oil safe for dogs? Let’s take a look.
What Is Eucalyptus Oil?
Eucalyptus oil is an essential oil that is distilled from the leaves of certain species of eucalyptus tree, also known as blue gum tree. Eucalyptus trees are native to Australia but are now widely grown worldwide as ornamental trees and for their medicinal properties (3).
Leaves of the eucalyptus (usually Eucalyptus globulus (4) but there are other varieties (5) used for essential oils) are chopped and placed into distilling apparatus (6). This sends steam through the leaves, which collects the oil as it goes. Once the steam reaches the top of the apparatus, it hits a cold surface where it condenses back into liquid water and oil. These are collected, and left to separate—like most oils, the essential oil floats on the surface of the water, meaning separating the two is easy.
Eucalyptus oil is mostly made of eucalyptol, also known as cineole (7). This active ingredient has been used for thousands of years for a variety of medicinal uses, as well as being used in foods, perfumes, and pesticides (6). Eucalyptol is thought to have anti-inflammatory effects, and has historically been used to treat dental disease, respiratory problems, headaches and head lice (8, 9, 10, 11, 12).
Is Eucalyptus Oil Safe for Dogs?
Whether or not eucalyptus oil is safe for dogs is a bit of a minefield. Not only have there been very few studies done, there are a range of products available, some with more eucalyptol than others, making any definitive answer difficult.
The ASPCA lists eucalyptus as a toxic plant to dogs and the Blue Cross agrees, listing it as “very poisonous to dogs” due to the eucalyptol the plants contain. Dogs are not allergic to eucalyptus oil, but eucalyptol may still be toxic due to liver or kidney damage (13, 14).
Eucalyptus essential oil is a purified, concentrated form of the plant, which means it’s more potent, and therefore more dangerous. It is toxic when ingested, causing vomiting, diarrhea, depression, lethargy, and seizures in humans, with a dose of just 3.5ml being known to be fatal to an adult human, although some people have recovered from higher doses than this (15, 16, 17). It appears that the symptoms cannot be accurately predicted by the dose, but we know that children are known to be more susceptible to the effects (18). But we don’t know how much eucalyptus oil is toxic to dogs.
Animals can also absorb eucalyptol through their skin, meaning that essential oils placed directly onto the skin can also cause symptoms (19). This is also true of diffusing eucalyptus oil, which can land on animals and be absorbed, or groomed off and ingested. Diffusing eucalyptus oil and dogs are a bad combination—so keep your dog well away from your diffuser, ideally in another room.
Eucalyptus Oil Benefits for Dogs
Interestingly, it’s unclear whether eucalyptus oil has any benefits in humans, let alone dogs. The US National Library of Medicine advises there is not enough evidence to recommend it for any of the diseases it has historically been used for (18). The European Committee on Herbal Medicine Products, on the other hand, concluded that eucalyptus leaf can be marketed for use for a “cough associated with a cold”—not because there was evidence of effectiveness, but because the treatment gets an herbal medicine exemption (20).
So, what about dogs? Well, there are no studies proving a benefit to dogs. It’s likely that, at the right concentrations, lemon eucalyptus oil repels fleas and other biting insects (21)—but it’s not clear whether those concentrations of essential oils are safe for dogs or not. There’s also some evidence that eucalyptus oil helps reduce pain from gout arthritis in mice (22). Whether this is true of other forms of arthritis, and in other species, is yet to be seen.
Other than the possible repellent effect, it looks like eucalyptus oil doesn’t have any clear benefits for dogs.
Pet Products That Contain Eucalyptus Oil
Despite this lack of evidence, plenty of pet products contain eucalyptus oil. While many use it simply as a deodorizer, some include it for its possible antibacterial, anti-inflammatory, and insect-repellent effects.
Eucalyptus oil can be found in dog shampoos and sprays as a deodorant. Ear wipes and cleaners also sometimes include eucalyptus oil, although whether for the bug-repellent properties or nice scent, it’s not clear. There are also natural flea spot-ons, collars, and powders available that contain lemon eucalyptus oil for dogs.
While these products probably contain very little eucalyptus oil, and it’s usually very dilute, there is still a potential risk to your pet if you use them. The truth is, we just don’t know how much eucalyptus oil is toxic. Even if we did, every dog is different, and a dog’s susceptibility to eucalyptus may also change over time—for instance, if the dog develops liver disease or develops a skin disease that causes them to groom themselves more.
“Natural” products don’t necessarily have the same rigorous testing as medications, and this can lead to toxic products making it onto the market. ASPCA Animal Poison Control has had several cases of side effects and even death from “natural” flea products containing essential oils (23).
Eucalyptus Oil for Fleas on Dogs: Does it Work?
There is some evidence that eucalyptus oil, topically applied, might help to get rid of head lice in humans (18). However, lice and fleas differ in one major aspect—head lice cannot live without a human, so topical applications can kill all lice in an infestation. Fleas, on the other hand, regularly hop on and off pets, spend time in the environment, and conduct large parts of their life cycle in your carpet and home.
While a topical application of shampoo or oil might kill the fleas on your pet, 95 percent of the infestation is safe from topical flea treatments. In addition, you’ll need highly concentrated eucalyptus oil treatments to kill fleas effectively—and this could be enough to be toxic to dogs.
While there is currently no evidence that eucalyptus is a safe and effective flea repellant for dogs, the Centers for Disease Control does consider it to be effective to repel mosquitoes in humans (21). However, it only lasts eight hours after application to human skin—a dog’s fur and differences in the skin layer may affect the time it works for dogs, and regular application may be dangerous. More evidence is needed for its use as a flea preventative in dogs.
Eucalyptus Oil and Dogs: Precautions to Take
With no proven benefits, and evidence that eucalyptus oil is bad for dogs, it might be best to avoid using eucalyptus oil altogether on your dog, unless prescribed by a holistic or herbal veterinarian, who may use safe doses of eucalyptus as part of a treatment plan (24).
If you do use eucalyptus oil or eucalyptus products for dogs, here are some safety aspects to consider:
- Never use concentrated eucalyptus oil—it should be properly diluted.
- Never apply products to broken skin
- Never use eucalyptus oil, no matter how diluted, on small dogs and puppies
- Don’t use eucalyptus oil on your dog if your cat could come into contact with it
- Don’t use eucalyptus oil in a diffuser in the same room as your pets
There is no good evidence to support using eucalyptus oil in pets, but that hasn’t prevented it from being included in a number of pet products. While these small doses are likely to be safe, it’s best to remain cautious, as eucalyptol is known to be extremely toxic in the wrong concentrations. If you do want to use herbal medicine on your dog, talk to a member of the American Holistic Veterinary Medical Association, who will be able to provide you with advice and guidance about eucalyptus oil and dogs.
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