Warning – These 23 Essential Oils Are Highly Toxic To Cats
The use of essential oils has grown in popularity over the past few years, mainly because of their appeal to consumers looking for natural alternatives to conventional medicines. However, it is important to keep in mind that although these oils may have therapeutic benefits for you, you need to consider your pets and how they will be affected. This is important to know.
Why Are Felines At Risk?
A cat’s anatomy, physiology, and behavior are very different to those of humans – and even dogs. Here are a few things that make a cat especially at risk with regard to the harmful effects of essential oils.
● They have a smaller body size compared to larger pets. This makes a typical safe dose of essential oil possibly toxic for them.
● They have thinner skin compared to larger mammals. This makes it faster for chemicals to penetrate and reach their circulation.
● Cats do not produce an important liver enzyme called glucuronyl transferase  which prevents them from metabolizing certain chemicals such as the phenolic substances found in some essential oils. This causes these chemicals to accumulate in their body rather than be processed by the liver, therefore producing toxic effects.
● Cats are curious and inquisitive creatures making them susceptible to accidental exposures to a toxic substance.
● They also groom their body quite often. This increases the likelihood of a substance reaching their mouth from a contact on their fur.
● Like dogs, a cat’s sense of smell is stronger than ours. What smells good to us may be overpowering and irritating to them.
Why Are Some Essential Oils Harmful To Cats?
Essential oils are the volatile, organic components of fragrant plant matter and contribute to a plant’s characteristic fragrance and taste. Essential oils are called essential not because they are a “must” or “necessity” but because they are derived from the essence of a plant. This means that essential oils are a concentrated substance that is composed of the chemicals contained by the representative plant. This is an important point to remember since a plant in its natural form may not pose a danger to pets but when it is converted to an essential oil that’s a no longer same story. Paraphrasing the statement of the “father of toxicology” Paracelsus, he said: “The dose makes the poison”.
Examples Of Essential Oils That Have Been Documented As Dangerous To Cats
Camphor is a fragrant aromatic essential oil commonly used for its topical analgesic and decongesting vapor properties. Camphor is usually found in vapor rubs, balms, liniments, muscle oils, and ointments. When toxic exposure occurs, it often causes skin irritation, vomiting, diarrhea, depression and in rare circumstances, seizures.
Similar to camphor, eucalyptus is used as an ingredient for vapor rubs, muscle creams, and room fragrance due to its fresh minty feel and fragrance. Exposure to eucalyptus produces irritation of the cat’s mucous membranes, vomiting, and diarrhea.
Most of the essential oils from citrus fruits are toxic to cats because they contain the toxins linalool and limonene. This includes essential oils from lemons, tangerines, grapefruits, mandarin oranges, limes. Citrus oils are usually found in products marketed for pest control. This includes flea collars, sprays, and dips. The most common manifestations of citrus oil toxicity include hypersalivation, cold skin, tremors and uncoordinated movement.
Bergamot is another example of the citrus fruit family; Bergamot is more commonly used as a fragrance than for therapeutic purposes. Cats that are exposed to a significant amount may exhibit vomiting, diarrhea, and skin irritation that is worsened by sunlight.
Bay Laurel And Clove Oil
Bay laurel oil is a mild antiseptic and antispasmodic used for wounds and stomach cramps. Clove oil is a component of tooth drops and is known for its anesthetic effects. Both are toxic to cats because they contain the chemical called eugenol. Eugenol can cause severe gastric distress in cats when exposed to large amounts.
Citronella is a popular ingredient in natural insect repellants. It is also available as candles or oil burners used to deter mosquitoes. However ingestion by cats can cause them to vomit and aspirate.
Oregano oil is often used as a flavoring ingredient but can also be used as a fragrance for room diffusers. Toxic exposure to oregano oil can cause gastric irritation to cats. 
Tea Tree Oil
Tea tree oil is a popular and potent antiseptic. It is used in a wide array of products ranging from soaps, shampoos, foot spray, cleansers, and even anti-flea drops. Pure tea tree oil is toxic to cats even when a small amount is used topically. In fact, there is a documented case in which three cats showed signs of dehydration, hypothermia, nervousness, and eventually slipped into a coma after being exposed to the oil. 
Cinnamon essential oil is used as a health supplement, food flavoring and as an ant repellant. Cinnamon bark oil exposure can cause dangerously low levels of blood sugar, liver damage, and irregular heart rates in cats. 
Geranium oil is known for it’s skin cosmetic properties and has been used a natural alternative for chemical tick repellants. Exposure can cause dilated pupils, trembling, depression, and weakness in cats.
Lavender oil is a popular essential oil famous for its calming and relaxing properties. It is used as a room fragrance to treat insomnia and in some cases flavoring for desserts. Some pet products contain small amounts of lavender oil as fragrance and are generally safe provided that proper use is followed. Toxic exposure to lavender can cause nausea, vomiting, and lack of appetite.
Pennyroyal is a plant member of the mint family. This plant is frequently used as a pesticide and insect repellant and as a mint flavoring for tea. Toxic exposure can cause liver damage in cats which can lead to bleeding, seizures, and death. 
Pine oil is commonly added to cleaning products for a fresh clean fragrance. It can also be found in some kitty litters as a natural scent. Pine oil is a mucous membrane irritant and can damage the kidneys and nervous system of cats.
Rue oil is derived from a plant called herb-of-grace. It is considered a toxic plant but has been used by herbalists as an antifungal, sedative, and treatment for indigestions. It is harmful to cats since it has been known for neurotoxic properties. 
Savory oil is not as common as the other oils in our list. This little-known oil is from a bush called summer savory and it is used traditionally as an antiseptic for cuts and abrasions and as a cooking seasoning. Since it has high phenol content, its use around cats is strongly discouraged because of the risk of toxicity. 
Another plant similar to pine trees, the oil from spruces is known for its characteristic clean pine smell. It is commonly used as a room deodorizer and can be used with other oils for an invigorating massage. Ingestion of the oil can cause seizures in cats. 
Believed to be an immunostimulant, thyme oil has found use as a health supplement used in cold weather. It can also be used a seasoning for meat dishes to add a fresh herb flavor and aroma. The chemical thymol found in the oil can be toxic to the nervous system of cats.
A popular essential oil, oil of wintergreen is used as candy flavoring for chewing gums, mouthwashes, and as a counterirritant for joint and muscle pain. Despite its usefulness, it is a danger to cats since when it enters the body it is metabolized into methyl salicylate which can cause toxicity similar to aspirin.
Sage oil is mainly used to help relieve stomach aches. It can also be used to help treat respiratory problems, menstrual cramps, fungal infections, dandruff and other skin problems. Cats that ingest sage oil can manifest with neurologic and cardiovascular symptoms like seizures and hypotension.
List Of Oils Regarded As Safe For Cats (In Small Amounts!)
Some essential oils have been reported to be safely used. However, these could still be harmful if used at too high a strength. Here are some essentials oils that have been reported as safe to use when properly diluted with a 1:50 ratio and only for short term use according to Dr. Richard Palmquist, Chief of Integrative Health Services at Centinela Animal Hospital. 
A great relaxant for anxiety, insomnia, and car rides. Take note that opinion on the use of lavender for cats is divided and consultation with a veterinarian is highly advisable before using.
A diuretic and appetite suppressant used for normalizing weight.
Fennel oil supports normal hormone function and can improve a sluggish metabolism.
Reported to have a potent healing property that enhances wound regeneration and nerve repair.
Known to increase the fighting power of the immune system and can be a supportive treatment for cancer.
Regarded as a great essential oil for treating gastrointestinal problems in cats.
Another issue with essential oils is the question of quality. Although pure essential oils may be dangerous because of their high concentrations, diluted poor quality oils are not necessarily safer. The “extenders” and impurities in these cheaper oils also add another “wild card” element of danger to cats.
There is certainly a place for the use of essential oils in our lives. Unfortunately, with the benefits comes certain risk. When using essential oils always make sure to follow the instructions and to store them where your pet can’t reach i.e. in a locked cabinet. A safer alternative to essential oils may be hydrosols available in the market. Hydrosols are herbal distillates that are less concentrated than essential oils and comprised mostly of water. Although these are relatively safer, it would still be a good idea to consult your veterinarian whenever you consider buying hydrosols.
 Glucuronidation. http://vetbook.org/wiki/cat/index.php?title=Glucuronidation
 Pet Aromatherapy And Essential Oils: What You Need To Know. http://www.huffingtonpost.com/richard-palmquist-dvm/pet-aromatherapy_b_877199.html
 Oregano. https://www.aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants/oregano
 Australian tea tree (Melaleuca alternifolia) oil poisoning in three purebred cats. http://journals.sagepub.com/doi/10.1177/104063879801000223
 Cinnamon. http://www.petpoisonhelpline.com/pet-safety-tips/nutmeg-cinnamon-toxicity/
 Pennyroyal Oil Poisoning in Cats. http://www.petmd.com/cat/conditions/poisoning-toxicity/c_ct_pennyroyal_oil_poisoning
 Rue essential oil information. http://essentialoils.co.za/essential-oils/rue.htm
 Savory oil. http://aromatherapybible.com/savory/
 Spruce Essential Oil. http://www.floracopeia.com/Essential-Oils/essential-oils-sub/organic-spruce-oil.html