Eventually, all great things must come to an end. With essential oils, it is important to store them properly in order to prolong their shelf life. Avoid exposure to the air, light, and high temperatures, which can cause and/or speed up chemical changes in essential oils. Also, remember to store essential oils safely, away from children and flames.

To understand the reactivity of essential oils, it’s good to know a little basic essential oil chemistry. Read more to learn which three elements combine in various ways to make up essential oils.

Try to use essential oils within a year or two of purchasing. Generally, lightweight essential oils have a shorter shelf life and heavier oils have a longer shelf life.Household cleaning recipes are good for using essential oils that are nearing their expiration date.

Proper Storage of Essential Oils

When it comes to essential oils, three main things can shorten their shelf life: exposure to air, sunlight and heat. In addition, there are safety considerations. Keep essential oils out of reach of children, and away from flammable areas.

Avoid exposure to air

Oxidation, or exposure to oxygen, can change the chemistry of an essential oil. It can increase the possibility of being skin sensitizing and reducing therapeutic benefits (1). According to Tisserand & Young, scientific studies have demonstrated reduced antibacterial activities of essential oils exposure to oxygen (1).

To reduce oxidation, make sure containers have a screw cap that seals tight. Drop dispensers are better than an open pour top in reducing exposure to oxygen and the amount of oil dispensed. In addition, choose small bottles with minimal airspace.

Avoid exposure to sunlight

Exposure to light can speed up chemical reactions, also called photocatalytic activity (2). Choose colored glass bottles, and store oils in a closed area away from sunlight.

Avoid exposure to heat

Keep it cool! Like sunlight, heat can also speed up chemical changes. The rate of deterioration of essential oils doubles with every 10 degrees Celsius of increased temperature (2). Heat increases the kinetic energy of the atoms that make up an essential oil, making them collide into each other at a faster rate (2).

Also, avoid storing essential oils in plastic containers and certain types of metal. Further, avoid essential oils with a built-in plastic dropper. Plastic can degrade physically or chemically upon contact with essential oils. The corroded plastic can then be absorbed into the oil (2). This can add toxic and unhealthy components, destroy aroma, and ruin the container to increase oxidation.

Store with safety in mind

Remember to store essential oils in a child proof area. It can be dangerous for a child to get into essential oils, which can cause poisoning, damaged skin, and organ toxicity.

In addition, essential oils are quite flammable, with a low flash point. This is the temperature at which they can catch fire. Keep them away from heat and flames, such as from candles.

Avoid contamination

Try not to get other essential oils, carrier oils, or ingredients of any type into your bottle of essential oil. Only use clean pipettes to extract oil. Avoid “double dipping” that can lead to cross contamination and shorten the shelf life of your oil.

Essential Oil Chemistry Lesson

Do you remember the Periodic Table of Elements? Elements, as you may recall, are the simplest component of a substance that cannot be broken down by a chemical reaction. Essential oils ONLY contain a combination of three different elements.

These three elements are carbon, hydrogen, and oxygen. Each of these elements are very light in molecular weight. They are located at the top of the periodic table. Heavier elements are listed at the bottom of the periodic table.

The elements of carbon, hydrogen, and oxygen can be combined in a vast variety of ways to create essential oil chemical constituents. Chemical constituents make up an essential oil.

Further, these light-weight elements have a small number of subatomic particles (protons, electrons, neutrons) in their atom. Heavier elements weigh more because they have more subatomic particles.

Within an atom, the number of protons is equal to the number of electrons. Electrons fly around the outer shell of atoms. Elements are more reactive when their outer shell of electrons is not filled. Carbon, hydrogen, and oxygen like to combine with other elements to fill their outer shell of electrons.

Molecular Weight of Essential Oil Elements

  • Hydrogen – 1
  • Carbon – 6
  • Oxygen – 8

Elements Combine to Form Compounds

When one element combines with another different type of element, it’s called a compound. An essential oil is a mixture of hundreds of light weight compound combinations of hydrogen, carbon, and oxygen (2).

These light-weight combinations of compounds are quite volatile. That is, they are both chemically reactive and evaporate quickly.

The lighter the essential oil, the more volatile. This also causes it to have a shorter shelf life. Monoterpenes, which are the lightest constituents found in essential oils, are dominant in citrus oils as well as pine, juniper berry, and fir essential oils.

Determining the Shelf Life of Specific Essential Oils

As a general rule, the lightest essential oils have the shortest shelf life. The heavier oils have a longer shelf life. Sometimes, essential oils rich in antioxidants, can defy this rule.

If you store your oils properly, and open them once in a while to use them, try to follow these guidelines.

  • Use light essential oils, like citrus oils within a year (1).
  • Use medium weight essential oils within 3 years.
  • Heavier essential oils can last 5 years, or maybe longer.

In ideal locations, an essential oil stored in a dark place, in cool temperatures, and in a sealed amber glass container, can last up to 6 years (3). Further, antioxidant ingredients such as rosmarinic acid or vitamin E can be added to a recipe, blend, or single note to help reduce oxidation. This can help to increase the shelf life.

What can you do with essential oils nearing their expiration date?

I like to make cleaning supplies with my essential oils that need to get used. Try one of the recipes listed below.

All Purpose Green Cleaner Ingredients

  • 70 drops of essential oils (including citrus oils, rosemary, peppermint, pine, etc.)
  • 1 tsp of liquid castile soap
  • 1 cup of white vinegar
  • 1 cup of witch hazel
  • 5 cups of water
  • 1 eight cup spray bottle

All Purpose Green Cleaner Instructions

In the spray bottle, combine the essential oils with the liquid soap. Add in the vinegar and witch hazel and shake. Finally, add the water and shake again. To use, shake and spray.

Avoid use in close proximity to pets and small children. Wear gloves when using cleaning supplies. Avoid certain essential oils with certain medical conditions.

Bathtub Scrub Ingredients

  • 1 Tbsp of liquid castile soap
  • 10 drops of essential oil, such citrus oil, rosemary, or pine
  • 1 cup of water
  • 1 cup of baking soda

Bathtub Scrub Instructions

In a 3-cup glass storage container with a lid, combine the castile soap with the essential oils. Mix in the water and baking soda. To use, apply about a ¼ cup onto a surface and scrub to clean.

Avoid use in close proximity to pets and small children. Wear gloves when using cleaning supplies. Avoid certain essential oils with certain medical conditions.

References

  1. Tisserand, R. & Young, R. (2014). Essential Oil Safety, Second Edition. Churchill Livingstone Elsevier.
  2. Clarke, S. (2002). Essential Chemistry for Aromatherapy. Second edition. Churchill Livingstone Elsevier.
  3. Buckle, J. (2003). Clinical Aromatherapy. Essential Oils in Practice. Second Edition. Churchill Livingstone.