To complement the MASSAGE Magazine article, “Aromatherapy for Massage Therapists: The Importance of High-Quality Therapeutic Essential Oils,” by Dorene Petersen, in the April 2012 issue. Article summary: Introducing essential oils into your massage practice can significant therapeutic value for your clients; however, buyer beware. Your end results will depend not just on your expert massage skills, but on the quality of the essential oils you stock in your clinic.

by Dorene Petersen

Be aware: a higher price does not necessarily mean higher quality. It is important to check all oils thoroughly regardless of price. Note: A price that is very low comparatively may indicate the oil is not what it is labeled, is diluted in a base oil, or is otherwise adulterated. Many expensive oils, such as rose (rosa damascena) and neroli (citrus aurantium var. amara), are sold diluted in a base oil, such as sweet almond, or even a more sinister diluent, such as dipropylene glycol or diethyl phthalate.

Some essential oils are particularly expensive or rare like rose and jasmine (jasminum officinale) oils. They are more likely to be extended or even be completely synthetic. Rose oil is extremely expensive. Anywhere between 2,500 and 4,500 pounds of rose petals are required to create 1 pound of rose absolute. One drop of rose otto is the product of 2,000 hand-harvested rose petals. When you consider this, it is easier to understand why a lot of the rose oil available commercially is synthetic.

Diluted and extended oils pose problems for the massage therapist or aromatherapist. Diluents, such as diethyl phthalate, sometimes referred to as DEP, can cause toxic reactions when taken orally or if absorbed through the skin.

Diethyl phthalate is a permitted substance in fragrance products where skin contact is minimal. It is made from ethanol and phthalic acid. It has a bitter and unpleasant taste and can be irritating to mucous membranes. When absorbed through the skin, it depresses the nervous system, and current research indicates it may have possible cancer-causing effects as well.

Diethyl phthalate is most often found in sandalwood (santalum album) and benzoin oils. A simple test for diethyl phthalate is to put 1 drop of the oil on the tip of your tongue. If the oil contains diethyl phthalate, your tongue will feel numb. Note that rose oil is an exception and can also make your tongue numb, though it is not necessarily adulterated. Rather, this is the analgesic action of eugenol naturally found in small quantities in rose.

Propylene glycol, sometimes referred to as DPG, is another diluent that should not be used in any essential oils intended for clinical aromatherapy. It is a colorless liquid that gives essential oils a sweet taste. It is absorbed through the skin better than glycerin, but has been linked to sensitivity reactions. It is often found in expensive oils, such as sandalwood, and is usually not indicated on the label.

An essential oil may also be extended. Extenders are inexpensive aroma materials that may or may not have an identical fragrance; they are usually synthetic, but may be natural. The term “nature identical” usually refers to a chemically synthesized version of the oil. Nature identical oils are not suitable for clinical therapeutic aromatherapy.

Dorene Petersen is president of the American College of Healthcare Sciences ( and chair of the Aromatherapy Registration Council. She has authored several textbooks used in aromatherapy courses, and her articles have appeared in Alternative Therapies in Clinical Practice, The News Quarterly and Making Scents, among others.