The dangers of essential oils: Why natural isn't always safe

At first thought, diffusing essential oils seems totally safe. How harmful can it be to enjoy scents like lavender, lemon and eucalyptus? The rise of brands such as Doterra and Young Living, beautiful diffusers that match any home decor and the new trend of putting essential oils on cloth face masks makes this wellness staple seem totally harmless. 

Words and phrases like "all-natural" and "therapeutic" make it easy to gravitate toward oils with rich scents. People often assume "natural" means safe, but there are plenty of natural compounds and chemicals that aren't safe (may I offer mercury as an example) and plenty of "good" substances that have shown no benefit in research studies (echinacea isn't as effective as many people think).

This concept applies to essential oils, too. Yes, they're natural and plant-derived, but it's worth taking a closer look before popping just any oil into your diffuser. 

The safety of any essential oil depends largely on the person using it, but like any plant product, these oils can contribute to skin irritation, respiratory symptoms and even hormone-related symptoms.

Essential oils and the endocrine system

Your endocrine system includes glands that produce hormones to regulate your metabolism, sleep, mood, appetite, sexual function, growth and much more. When these glands produce too much or too little of any hormone, it can result in symptoms including weight gain, mood swings, low libido, disturbed sleep, hot flashes and fatigue. 

Dr. Romy Block, board-certified endocrinologist and co-founder of Vous Vitamin, says essential oils can act as endocrine disruptors, which means they interfere with the natural production of your hormones. 

"These chemicals can either lower or raise the normal hormone levels in the body," Dr. Block says, "causing disruption of development, reproductive changes or even interference with the immune system."

There's not enough evidence about all essential oils as endocrine disruptors to make any blanket statements, Dr. Block says, but a handful of essential oils have been linked to hormone-related health complications. Research has shown lavender oil to be associated with early breast development in girls, for example. Lavender and tea tree oil are also thought to lead to a condition called prepubertal gynecomastia (abnormal breast tissue growth) in boys.

Dr. Block advises against diffusing lavender and tea tree oils because of the potential complications, particularly in children and teens. Pregnant women and people who have hormone-related medical conditions such as diabetes should talk to their doctors before using essential oils topically or with a diffuser.

Essential oils and allergies

The main and most immediate health consequence of using essential oils is probably allergy symptoms. You would know if you had an allergic reaction to an essential oil, because it would result in typical symptoms, such as itchy and watery eyes, runny nose, sneezing and congestions. Topical use of essential oils could result in dermatologic allergy symptoms, including redness, hives, itchiness and swelling of the skin. 

Dr. Sanjeev Jain, board-certified allergist and immunologist at Columbia Allergy, says that while allergy symptoms depend on the route of administration (inhalation versus topical application), it's not uncommon for people to experience both at the same time.

If you suspect you're having an allergic reaction to an essential oil, stop using the product, Dr. Jain says, and consult your allergist or dermatologist for further evaluation.  

"It's very important to know which extract is triggering a reaction and which extracts are safe for you to continue to use," he says. "You can be sensitized to multiple allergens at the same time, so it's important to get appropriately evaluated before continuing with the use of these essential oils or extracts." 

Unfortunately, allergies to essential oils require strict avoidance, Dr. Jain says. If you're contact-sensitive only, it might be possible to use an essential oil diffuser, if you don't develop respiratory symptoms. Make sure to carefully handle the oils to avoid contact with your skin. 

Which essential oils are safe?

As of this writing, there's not enough evidence about essential oils to make a definitive "safe" and "not safe" list. Right now, most essential oils are considered safe with proper use, and various studies report health benefits of different essential oils. That doesn't mean they're without drawbacks, though. 

For example, a 2019 study shows that eucalyptus and ginger essential oils might support immune health -- but the researchers point out that most studies have taken place in eastern countries where the compounds are "traditionally used and valued" and that the entire, pure oil used in studies does not always match what you find on store shelves. 

Here are just a few more examples of the benefits and drawbacks of essential oils: Lavender is known to help with sleep and relaxation but, as mentioned above, it could act as an endocrine disruptor. 

• Eucalyptus is soothing but it can cause seizures if ingested. 
• Chamomile can help you unwind, but people with allergies to ragweed, daisies and other plants may have severe reactions. 
• Peppermint is loved for the cooling effect it has on skin but it's also known to cause skin rashes, burning and flushing, among other side effects.

Again, it's hard to make a black-and-white list of essential oils to avoid. Because people can have different reactions to different oils: Only the individual can know which ones to avoid. A quick internet search will return hundreds of lists that don't match, so it's really up to you to vet the risks of the essential oil you want to use and to use them safely. 

What about pets?

If you have a fur baby or several, you might've wondered whether essential oils are safe for pets. Personally, I have an orange tabby cat that I love more than most people. I also love peppermint essential oil, so I was sad to learn that peppermint oil is a no-go for kitties. 

According to the ASPCA, cats are especially sensitive to essential oils, says Lambert Wang, co-founder of Cat Person. "While the safety of essential oil use is individual and varies from cat to cat, a general rule of thumb is to never keep your cat in a room where oil is being diffused," he says. 

As for dogs, the American Kennel Club says essential oils can irritate a dog's skin if applied topically, and ingestion can cause gastrointestinal upset. 

Keep in mind that cats and dogs have much stronger noses than humans do, so a scent you perceive as mild could really irritate your furry friend.

Keep your doors open so your pets can move away from areas of diffusion, and never apply essential oils directly to your cat or dog. Pay close attention to your pets if you diffuse essential oils, Wang says. "If you notice a change in behavior after using essential oils, discontinue use immediately and visit your vet." 

As always, the safety of a particular trend comes down to you, your health and your preferences. Take into consideration factors like allergy symptoms, sleep quality, pets and other members of your household.

How to safely use essential oils

If you want to enjoy essential oils, these tips can keep aromatherapy safe for you and your pets.

• Talk to your doctor before use if you're pregnant or have any medical conditions.
• If you want to use essential oils on your pet, talk to your vet.
• Stop diffusing essential oils that give you allergy symptoms, such as coughing, sneezing or water eyes.
• Try a patch test before using an essential oil topically. To perform a patch test, place a diluted drop of oil onto a small portion of your skin. If you develop dermatologic symptoms, wash it off and don't use that oil on your skin. 
• Don't keep your pet in a room with an essential oil diffuser running, and leave doors open so they can freely move about.

Read more: Terpenes, the smelly compounds that can benefit your health