Do Essential Oils Have Side Effects?

May 26th, 2021

A lot of people think natural ingredients are safe ingredients. They think natural ingredients don’t have side effects. This couldn’t be further from the truth. Many natural substances, including essential oils, are irritating and even highly toxic.

Essential oils are highly concentrated substances and they have the potential to cause harm. The rule “less is more” should be applied, especially when working with dogs/animals. 

There are also essential oils that are not recommended for use with animals, as they are harsh, irritating, sensitizing, and even toxic. For example Anise, Birch, Camphor, Cassia, Clove leaf and bud, Garlic, Oregano, Pennyroyal, Red and White Thyme, Tansy, Wormwood.

Do essential oils have side effects?

 A special mention must be made to Tea Tree Melaleuca alternifolia essential oil. Tea Tree essential oil has strong antibacterial, antifungal, antiviral insect repelling properties. There were reported cases when the oil was applied dermally to dogs and cats. In most cases, the oil was misused and high doses *. The increased demand and mass production of Tea Tree oil open the gates for adulterated and poor-quality oils to reach the market. This is resulting in more adverse reactions and irritations in humans and animals. We should not use undiluted Tea Tree oil on the skin because of the risk of sensitization **. And we must avoid old or oxidized oil. Try the more gentle yet powerful relative of the Tea Tree oil, the Niaouli, instead.

The potential side effects of essential oils include:

Skin reactions:

Skin reactions may vary from one individual to another. Always dilute oils with a carrier oil before applying it to the skin. Apply a small amount to a small skin area first to test for any reactions. If a reaction occurs, wash the area with unscented soap to remove the oil, and if needed, apply aloe vera gel or Soothing Antiseptic Spray.

Some essential oils are phototoxic. This means the reaction occurs in the presence of ultra violate light. Simply said, when the skin is exposed to sunlight. The affected area looks like a burn. 

Phototoxic oils are: bergamot, cold-pressed lime, cold-pressed grapefruit, cold-pressed lemon, cold-pressed sweet, orange, cold-pressed tangerine, cold-pressed lime. 

Asthma attacks:

While essential oils may be safe for most people to inhale, some people with asthma may react to breathing in the fumes. Asthma is a chronic condition that affects the airways. It causes wheezing and can make it hard to breathe. Some triggers include exposure to an allergen or irritant, viruses, exercise, emotional stress, and other factors.


Inhaling essential oils may help some people with their headaches, but inhaling too much may lead to a headache in others.

My friend Vaness Byrne from Top Tails grooming says: “I love working with essential oils. I find that almost all of the time an oil I know if an oil is needed or not because I either like the smell or don’t. And someone an oil I like on one day and I don’t like on another. For me, Ylang Ylang is a bit of a mystery. It’s not one of the oils that I’m not too fond of the smell of, but within a few minutes of being with it, I become very heavy and lethargic, and then I develop a deep heavy, dull headache that will last several hours. I can tolerate it if it is very diluted, but not if it is in a diffuser.”

 *Bell L.K, Holistic Aromatherapy for animals. Findhorn Press, USA, 2004

** Tisserand R, Young, R. Essential Oil Safety, Churchill Livingstone Elsevier, UK/USA 2014

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Just to let you know we LOVE the Comfort Blend we got from you at Crufts. The girls love the smell and try to lick it, and I find walks are a lot calmer these days. THANK YOU!! Calming Floral Spray is next on my list and maybe a burner with some stones.”
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