Do Essential Oils Expire?

When you have a large stockpile of essential oils, sometimes you don’t use them as fast as you expected. This inevitably leads to finding a dusty lavender, peppermint, or frankincense and the question of whether the oils can still be used. The answer to this question seems obvious—essential oils are not immune to the laws of nature so they must “expire.”However, the true answer to this question is a bit more complex.

When we say shelf life and expiration, we are referring to whether the essential oil still maintains its efficacy and safety. Due to the unique nature of essential oils, they can retain their benefits and preferred composition for long periods, but it depends on the oil and the way that it is stored.

We know that oxygen, heat, and light (UV rays) can degrade the therapeutic value and composition of essential oils. When it comes to heat, chemical reactions accelerate with increasing temperature, doubling after 10 degrees C (50 degrees F). This means that essential oils can undergo chemical reactions if they are exposed to high temperatures.

Similarly, ultraviolet (UV) light influences chemical reactions. UV light splits molecules apart by breaking bonds between atoms. This creates a highly reactive atom that collides with another oxygen molecule to create ozone. Ozone is very unstable and so the UV light is able to quickly repeat this process. Italian researchers reported that exposing lavender essential oil to UV light significantly deteriorated its composition and biochemical profile. The bottom line: UV light can damage essential oils.

When a bottle is opened and drops of essential oil dispensed, oxygen enters the bottle and fills the new empty space (headspace). The more oxygen that enters the bottle the more oxidation occurs. Oxidation is a chemical reaction that alters the chemical components of an oil, breaking them down into new constituents.

Published literature shows that essential oils like lavender, rosemary, pine, and cumin change when exposed to light or heat. They increase peroxide levels and their chemical composition is altered even at 100 degrees F. Some oils like pine may even change at room temperature. How much they change depends on the headspace in the bottle, actual ambient temperature, and exposure to direct sunlight.

There really is no blanket guideline when it comes to the stability of essential oils, nor a consensus about the exact conditions that may cause degradation because it will vary depending on the oil. For example, phenol-rich oils like thyme and oregano resist degradation because phenols are good antioxidants. Heavier weight sesquiterpene molecules are also more stable and resist chemical alterations better than lighter weight monoterpenes. Citrus oils that are predominantly the monoterpene limonene tend to easily change their composition during storage, especially if they have been opened.

In general, these storage guidelines should be followed:

  • Store essential oils in dark glass
  • Keep essential oils in a cool, dark place
  • Store them away from heat sources and direct sunlight exposure
  • Transfer opened essential oils into smaller bottles when you have used near 50% of the bottle
  • If essential oils become heated (e.g. a hot car), allow them to return to room temperature before opening
  • Consider storing citrus essential oils in a refrigerator—bring them to room temperature before use

The chemistry of an essential oil plays a significant role in how prone it will be to changing composition over time. Certain essential oil constituents are more prone to alteration than others.

Understanding that many variables contribute to the shelf life of an essential oil, and assuming proper storage has been maintained, the following can be used as a guide for essential oil shelf life:

 

Constituent Family

Shelf Life UnopenedShelf Life Opened 

Essential Oil Examples

Monoterpene1–3 years1–2 yearsGrapefruit, Lemon, Lime, Mandarin, Orange, Tangerine, Yuzu
Monoterpene + Monoterpenol1–3 years1–2 yearsPalo Santo
Aldehyde + Ester4–7 years2–3 yearsCassia, Cinnamon Bark
Aldehyde + Monoterpene/Alkene4–7 years2–3 yearsLemon Verbena
Aldehyde + Monoterpenol/Sesquiterpenol4–7 years2–3 yearsLemon Eucalyptus, Lemon Myrtle, Lemongrass, May Chang (Litsea), Melissa
Monoterpene + Ester4–7 years2–3 yearsBalsam Fir, Blue Spruce, Douglas Fir, Siberian Fir, Silver Fir, Spruce (Black)
Ester4–7 years2–3 yearsArborvitae (Western Red Cedar), Roman Chamomile, Wintergreen
Ester + Alkene/Ketone/Monoterpene4–7 years2–3 yearsHelichrysum
Ester + Monoterpenol4–7 years2–3 yearsClary Sage, Jasmine Absolute
Ester + Oxide4–7 years2–3 yearsCardamom
Ether + Monoterpene/Ketone4–7 years2–3 yearsFennel, Star Anise
Ketone + Monoterpenes4–7 years2–3 yearsCamphor, Dill, Sage CT alpha-thujone, Spanish Sage, Spearmint
Ketone + Sesquiterpene/Ether/Alkene4–7 years2–3 yearsDavana, Manuka, Turmeric
Monoterpene + Alkene/Sesquiterpene4–7 years2–3 yearsCelery Seed, Cypress, Frankincense, Juniper Berry, Pine (Scotch/ Scots), Pink Pepper
Monoterpene + Alkene/Phenylpropanoid4–7 years2–3 yearsRavensara
Monoterpene + Ether4–7 years2–3 yearsNutmeg
Monoterpene + Sesquiterpene/ Sesquiterpenol4–7 years2–3 yearsElemi, Kunzea, Yarrow
Monoterpenol4–7 years2–3 yearsHo Wood, Rosewood
Monoterpenol + Aldehyde/Monoterpene4–7 years2–3 yearsCilantro, Citronella, Magnolia, Marjoram
Monoterpenol + Ester/Monoterpene4–7 years2–3 yearsBergamot, Coriander Seed, Geranium, Lavandin, Lavender, Neroli, Palmarosa, Petitgrain, Rose, Spike Lavender, Tea Tree (Melaleuca)
Monoterpenol + Ketone4–7 years2–3 yearsCornmint, Peppermint
Monoterpenol + Phenylpropanoid/Oxide4–7 years2–3 yearsBasil (Sweet)
Monoterpenol + Oxide4–7 years2–3 yearsRosalina
Oxide + Monoterpene/Monoterpenol/ Alkene4–7 years2–3 yearsBay Laurel (Laurel Leaf), Eucalyptus, Cajeput, Fragonia, Myrtle, Niaouli
Oxide + Ketone/Monoterpene/Alkene4–7 years2–3 yearsRosemary, Sage CT 1,8-cineole
Phenol + Monoterpene/Sesquiterpene4–7 years2–3 yearsAjowan, Oregano, Thyme
Phenylpropanoid + Monoterpenol4–7 years2–3 yearsBasil (Tropical)
Phenylpropanoid + Sesquiterpene/ Monoterpene4–7 years2–3 yearsAllspice, Cinnamon Leaf, Clove Bud
Sesquiterpene + Alkene/Ester/Monoterpene4–7 years2–3 yearsBlack Pepper, Ylang Ylang
Sesquiterpene + Oxide4–7 years2–3 yearsGerman Chamomile
Sesquiterpene/Sesquiterpenol7–12 years5–10 yearsAtlas Cedarwood, Blue Tansy, Copaiba, Ginger, Himalayan Cedarwood, Patchouli, Sandalwood (Australian, Hawaiian, Indian, New Caledonian), Spikenard, Texas Cedarwood, Virginia Cedarwood, Vetiver
Sesquiterpene Ether + Sesquiterpene7–12 years5–10 yearsMyrrh
Sesquiterpene Ketone7–12 years5–10 yearsBuddha Wood
Sesquiterpenol + Alkene/Sesquiterpene7–12 years5–10 yearsAmyris, Carrot Seed, Blue Cypress

With proper storage (cool, dark place away from heat sources), essential oils have a long shelf-life. Indeed, researchers found that peppermint oil properly stored for about 50 years—stored in a cool dark place in dark glass and sealed with wax—met or exceeded the quality and antimicrobial activity of a fresh sample. This demonstrates that oils can maintain their quality and safety for years.

Unfortunately, most consumers will not be able to perform a chemical analysis of the essential oil to determine if the composition of a stored oil has changed. Instead, consumers must rely on their senses. A good indication of an altered essential oil is its aroma. If the oil smells differently, this is an indication that the chemical composition has changed. Citrus oils may have white chunks floating in them as they go bad. Those essential oils that are labeled for consumption may have an altered taste. Lastly, altered essential oils may cause greater skin irritation.

So, the answer to the question from the beginning is—it depends? It depends on the oil and its composition as well as storage conditions.

REFERENCES:

Gismondi A, Canuti L, Grispo M, et al. Biochemical composition and antioxidant properties of Lavandula angustifolia Miller essential oil are shielded by propolis against UV radiations. Photochem Photobiol. May-Jun 2014;90(3):702-8.

Turek C, Stintzing FC. Impact of different storage conditions on the quality of selected essential oils. Food Res Int. 2012 Apr;46(1):341-53.

Mehdizadeh L, Pirbalouti AG, Maghaddam M. Storage stability of essential oil of cumin (Cuminum Cyminum L.) as a function of temperature. Int J Food Prop. 2017; 20(Sup2):1742-50.

Gochev V, Stoyanova A, Girova T, et al. Chemical composition and antimicrobial activity of Bulgarian peppermint oils. Sci Papers. 2008;36(5):83-89.