dilutionHi Robert,
I’m having some trouble understanding my essential oil dilution research and was hoping you could clarify for me.

1.) Why is dilution so important if 95% of the oil evaporates when applying topically?

2.) Is dilution recommended due to sensitivities that could occur? I have used oils neat before and never had an issue.

Thank you for your time,

Hi Danielle,

It partly depends on why you are applying essential oils, and why to the skin. Much of my teaching is about cosmeceutical effects and products for skin care. Dilutions of essential oils are generally more effective in this area, because the skin does not respond well to concentrated EOs. They are drying, the risk of adverse reactions is increased significantly, and for skin care/personal care you simply do not need more than 1-5% essential oil.

About 5% of applied EO is absorbed into the body through the skin, but more if undiluted oils are used. When you first apply an EO to the skin, 100% of it is there for a while. This is when any adverse skin reaction will occur, so while it is true that most of it evaporates with time, this is not as relevant as the initial dilution.

Essential oil dilution is important for two safety reasons. One, to avoid skin reactions: irritation, sensitization and phototoxicity. Two, to avoid systemic toxicity, such as fetotoxicity, hepatotoxicity, carcinogenicity and neurotoxicity. Adverse skin reactions are obvious when they happen, but systemic toxicities may not be. Skin reactions are totally dilution-dependent, and safety guidelines exist to minimize risk. This does not mean of course that every time a person uses an undiluted oil there will be an adverse reaction. Many times there won’t. But more is not always better, and minimizing risk is generally a good idea. A phototoxic reaction for example, can be very, very nasty.

If you want to know more about what can go wrong and why, I would recommend my book Essential Oil Safety 2e.