Sensitization – “exposure to allergen that results in the development of hypersensitivity.” [1]

essential oil female back spa

So what is hypersensitivity? Is a hypersensitivity reaction the same as an allergic reaction?

Answer, yes. They are synonyms, BUT there are four different types of allergic reaction:
“a local or general reaction of an organism following contact with a specific allergen to which it has been previously exposed and sensitized; immunologic mechanisms gives rise to inflammation or tissue damage. Allergic reactions are classified into four major types: type I, anaphylactic and IgE dependent; type II, cytotoxic; type III, immune-complex mediated;type IV, cell mediated (delayed).”[2]

For the purposes of aromatherapy safety, any essential oil can become an allergen by using it undiluted on the skin; and this risk is there for all essential oils, including lavender. So while there are certain essential oils which have a known reputation for being potential allergens or with a reputation for sensitization, using any essential oil neat (undiluted) sets the individul up for a potential allergic reaction, leading to sensitization, and forever being allergic to that essential oil.


Robert Tisserand explains:


“Yes, sensitization is the process that takes place in the body that leads to an allergic reaction. They are not the same thing, but they are not totally different either. There are 4 types of allergic reaction, [3] but only two are relevant to essential oils. Type 4 (delayed hypersensitivity) accounts for 90% of allergic reactions. Type 1 is immediate hypersensitivity (generally not anaphylactic) and accounts for the other 10%. You could say the risk is potentially there for all essential oils, but this is a little unfair on the majority of oils, that have never been known to cause such reactions. I don’t like to assume risk that may not exist. The less you dilute the more you increase risk, but that doesn’t mean that undiluted copaiba oil is a greater risk than 1% cinnamon bark oil. It isn’t.”

To learn more, see the video which is a sample from Webinar 4 “Irritation and Allergy” from Essential Oils and the Skin 10-Day Series by the Tisserand Institute:

1. Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved
2. Farlex Partner Medical Dictionary © Farlex 2012

About Dietary Supplements

Under section 201(ff)(2)(A)(i) of the Act [21 U.S.C. § 321(ff)](2)(A)(i)], a Dietary Supplement is defined, among other things, as a product intended for ingestion.

Dietary supplements are neither evaluated nor regulated for efficacy or safety under the Dietary Supplement Health and Education Act (DSHEA) of 1994. In addition, FDA approval is not required for dietary supplements to be marketed.

Topical products and other products that are not intended for ingestion are not dietary supplements.

Whether or not they are intended for ingestion, medical claims make a product a drug under section 201(g)(1)(B) of the Act; meaning a dietary supplement with medical claims, is no longer a dietary supplements under section 201(ff) of the Act. Both Young Living and doTerra were warned by the FDA for selling essential Oil products which they marketed as dietary supplements, but which are offered for topical use and/or intended for inhalation.

A *true* dietary supplement will be formulated to provide nutritional benefits missing from the diet – that is why they are called dietary supplements – they supplement the diet. The FDA regulation DSHEA also allows products to be formulated for and marketed with claims that they will impact the structure or function of the body. What is a structure/function claim? This page answers that question: 

One thing I have read more than a few times, which is false, is that the FDA Mandatory Disclaimer mean the FDA has approved the product. It ACTUALLY means the opposite!

” If a dietary supplement label includes such a claim, it must state in a “disclaimer” that FDA has not evaluated the claim. The disclaimer must also state that the dietary supplement product is not intended to “diagnose, treat, cure or prevent any disease,” because only a drug can legally make such a claim. “

This is basically a consumer WARNING not a FDA endorsement!

Essential oils sold as “dietary supplements” are doing so in order to take advantage of two *loopholes*: many essential oils are Generally Recognized as Safe as food flavorings, and the laws regulating dietary supplements [DSHEA] allows them to be marketed with the structure or function claims which are not allowed for essential oils sold for topical or inhalation use. They are NOT selling them as “dietary supplements” because they actually supplement the diet in any way. No ones diet is missing essential oils. They do not contain vitamins.


Essential oils are occasionally ingested for medicinal/therapeutic purposes. Oral dosing has risks which often outweigh any potential benefits.

Dripping herbal essence of a vial over a spoon