Monoterpenes Matter

 Piper nigrum

Piper nigrum

A few weeks ago, we began discussing the importance of chemistry and of knowing the chemical profiles of the essential oils we use in determining the therapeutic use of the essential oils. We also discussed how plants of the same genus and species can produce wholly different chemical profiles based on many different environmental factors. If you are just joining the conversation, please look back at the previous articles, Chemistry Matters and Chemotypes Matter, for more information on these topics.

Today we are going to take a deep dive into specific chemical components, we will learn what the therapeutic potentials of these components are, and which essential oils have the highest amounts of these components.

Just a quick refresher, terpenes are the most prominent chemical compounds found in essential oils. In the terpene family there are two main groups, monoterpenes and sesquiterpenes. Within each of these groups there are individual molecules that have many different therapeutic properties. Sometimes generalizations can be made such as many monoterpenes may have an uplifting, energizing, clarifying, and restoring effect on the body. While sesquiterpenes in general are soothing and stabilizing/grounding.

However, when you take a deeper look into the world of essential oil chemistry, you will learn that it is not the individual compound that gives the essential oil its super power. Instead, it is the synergistic combination of a multitude of different compounds working together that creates the amazing results we have come to associate with the use of high quality essential oils.

Monoterpenes are made up of two isoprene units that combine together to form a 10 carbon unsaturated (contains double bonds, C=C) molecule. All monoterpenes have the same chemical formula, C10H16. The variation of how the carbon atoms are linked together is what creates the different monoterpene molecules. For example, each molecule in the figure below with the exception of isoprene, all have ten carbons and sixteen hydrogen atoms.

Common monoterpenes found in essential oils:


Top left to right: Isoprene (5 carbons only), Alpha-pinene, beta-pinene, delta-3-carene, d-limonene, camphene, myrcene. Bottom left to right: beta-phellandrene, sabinene, alpha-terpinene, ocimene, alpha-thujene, terpinolene, gamma-terpinene.

Many essential oils have monoterpenes in them in varying amounts. Monoterpenes have been studied for decades for their many therapeutic effects. A quick Google Scholar search on monoterpenes returned over 53K results. Many of these results revealed monoterpenes have been studied for their ability to inhibit bacterial growth, to be used as natural herbicides,as well as their role in prevention and inhibition in tumor growth.

Safety Considerations for monoterpenes:

Monoterpenes tend to be smaller molecules which means they tend to evaporate quickly. In a blend monoterpenes are usually the top note that you smell first because it evaporates once exposed to the skin, or warmer temperatures. Monoterpenes are also prone to oxidation, meaning when exposed to light, heat, and air, the double bonds in the monoterpenes combines with oxygen to oxidize the monoterpene. When a monoterpene has become oxidized, it is considered degraded. Oxidized monoterpenes can cause skin irritation. So it is important to keep all essential oils in a cool, dark place with lids tightly sealed to keep the essential oils from degrading too quickly. Never use oxidized or old essential oils on the skin as it may cause irritation and skin sensitization. Always dilute essential oils in a carrier oil before applying topically.

There are a couple of ways that you can know if your essential oil is old or expired and therefore at higher risk of oxidation. Check the expiration date of your essential oils. Contact the company that you purchased your oils from to find out when your batch was harvested. Keep track of the dates that you opened your essential oils to help reduce skin irritation due to use of oxidized oils.

Therapeutic properties of monoterpenes:

Monoterpenes are responsible for the tonic/drying effect on skin. Monoterpenes are also helpful in drying up an overproduction of mucus (otherwise known as mucolytic). Monoterpenes help to support the respiratory system, and are responsible for many of the antibacterial, antiseptic, antiviral properties in essential oils. Monoterpenes are natural air purifiers and deodorizers. Many monoterpenes are powerful at disrupting the body’s inflammatory response, and act as cooling, soothing agents to the musculoskeletal system.

Essential oils high in monoterpenes:

Black Pepper





Juniper Berry



Wild Orange


Siberian Fir

Sweet Marjoram


Uses of monoterpene rich oils:

Monoterpene rich essential oils are among my absolute favorites to use to support a variety of body systems in my own health and the health of my family. Many of these essential oils are especially powerful at supporting the immune system, the respiratory system, and supporting tight, sore, tense muscles. Emotionally, essential oils like citrus oils are joy inducing and uplifting to the mood. Essential oils like cypress, rosemary, sweet marjoram and siberian fir are especially helpful with supporting blood flow to the muscle cells after physical exercise. Supporting the muscles natural recovery process helping to ease soreness.

We are not done exploring the world of essential oil chemistry. There are so many chemical constituents to cover. Follow @essentialyogaspace on Instagram over the next couple of months, to learn about specific monoterpenes, the research to identify therapeutic potentials of specific monoterpenes and the best way to harness the power of these components by making essential oil blends.

If you have a specific essential oil that you would like me to study, please let me know in the comments below.

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