Do Essential Oils Go Bad?

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Are you wondering how long your essential oils will last you? Whether they’re still safe to use after a few years in your medicine cabinet? Maybe you’ve been told they don’t have an expiry date. This article is all about essential oils shelf life and how to best ensure you can enjoy your oils for the longest possible time.

Quality of Essential Oils

First and foremost, using pure essential oils is very important in aromatherapy.  It is the oils’ purity that determines how effective the desired aromatherapy treatment will be.

At times, bargains or cheap oils can be of poor quality. In other words, they are not made out of pure plant extracts, which is necessary if the essential oil should have therapeutic effects.  The best way to know if the oil is pure is by knowing its source and testing it through Gas Chromatography (GC) or Mass Spectrometry (MS). Testing an oil with GC/MS will give you its exact chemistry. However, it will not tell you the oil’s energetic quality or vibration.

Most manufacturers these days are really good about disclosing their oils’ GS/MS testing information as their desire, too, is to educate customers on oil quality, origins and use.  You can ask the manufacturers themselves – or find more information in my very detailed essential oil brand reviews.

Ideally, pure essential oils do not expire. They have antibacterial and antiviral properties and do not contain water. Hence, they don’t grow mildew, mold, or yeast. That being said, once they interact with outside properties such as heat and light, they do start to change.

Factors that Affect Changes in Essential Oils

Three most common outside forces that start changing the properties of essential oils, are:

1. Oxygen

Oxygen changes the chemical composition of essential oils as it reacts with some their constituents. A change in the chemical composition of the essential oil means that it’s no longer the same as before. You will not know its contents until it’s retested.

A study found that about 66.4% of the monoterpene content in Lemon essential is gone after 12 months of daily exposure to air. When the exposure is reduced to once a month, the content degradation is also minimized.

You should note that exposure to air does not hasten the oil’s expiration. It changes its composition so that it will not function as good as when it’s pure (at the time the bottle is first opened).

2. Heat

 There have been studies proving that extreme heat can actually change the chemical structure in the essential oil. While there doesn’t seem to be concrete proof of this yet, makers are careful about the temperature of the room in which the essential oils are stored.

3. Light

Light promotes the formation of any oxygen-free radicals. These are highly reactive and could change the essential oil. A study done with Sweet Orange essential oil shows that exposure to UV light for about 50 minutes leads to dramatic changes. Some of its chemicals were increased, and some were decreased. The most shocking thing is that there were 12 new chemicals present in the oil.

The best way to avoid making changes in the original composition of the oil is to exercise proper oil storage.

Guide on Storing Essential Oils

An essential oil can’t stay fresh without proper storage. It does not react well to changes in temperature, and since you’ve spent a considerable amount of money in it, you might as well look after it properly. Otherwise, you’ll lose its therapeutic benefits. Luckily, storage solutions for an essential oil are easy.

1. Bottling

Since ultra-violet light affects the composition of the essential oil, make sure that you put it on a dark-colored glass. Dark amber is the most common shade of glass. However, you can also choose one that is violet, green, or blue. They offer the same level of protection.

Putting your essential oil on a dark glass does not mean you can expose it directly to the sun. While the glass helps screen the UV light, natural heat will still speed up the oxidation process. So, be sure to still keep it some place dark and cool.

Cap the glass tightly so as not to expose it to oxygen. If not, some of the chemicals will evaporate, especially if the oil is not 100% pure.

2. Cooling

Essential oils are prone to oxidation under heat and temperature variations – especially citrus oils. The same is true for massage oils and carrier oils. To avoid this, you can store them in your refrigerator. Be careful not to set the temperature too cold, about 5 to 10 degrees Celsius is enough. In fact, it’s much better than storing your oils on the kitchen’s window ledge.

Citrus essential oils will not change under the prescribed temperature; however, Aniseed, Rose Otto, Fennel, and Star Anise may solidify. So, before you use any of them, allow them to sit for a few hours. This will return them to their normal form. For the Rose Otto, you can just hold it in your hands for a few minutes. Never put the oils under the sun in order to hasten the process. Let it the natural wax dissolve without exposing it to UV light.

 In summer, when it’s especially hot, essential oils can be particularly vulnerable. Store them in the fridge and take them out about 12 hours before you use them. This way, they can adjust to the room temperature naturally. Give it a quick shake to ensure that the waxy particles are completely dissolved.

3. Boxing

If you don’t have any space in your fridge, use a storage box instead. It’s good enough to keep some types of oil. You just have to keep in a place that has the least or no changes in temperature. You also have to remember that some oils are moderately volatile, so they will evaporate quickly if you don’t cap it tightly. Also, don’t leave them lying around after you use them. Put them back in the box.

4. Storing

Essential oils are flammable. Thus, do not leave them near fires, candles, cookers, or any other sources of ignition. Don’t forget to keep them away from children. The essential oil is not something they can play with.

Never keep undiluted oils into plastic bottles. Why? Most oils will eat into the material and start degrading the plastics. Diluted oils like lotions and massage oils might be stored in plastic since the concentration of essential oils is lowered through the mixture with the other components.

Shelf Life of Essential Oils

As said, pure essential oils don’t go rancid, but they can oxidize and deteriorate over time. In other words, they slowly lose their aromatic quality and therapeutic value. In order to know just how long an essential oil’s chemical stability, you should check the oil’s individual shelf life.

Aromatic oils are mixtures of several compounds. If this mixture remains stable, do not change in chemistry, and keep their therapeutic value for a long time while in storage, then they have a long shelf life. The shelf life of each oil differs from each other and is mainly influenced by a lot of factors. These factors include the quality of the plant, when and how the plant is harvested, the method used during distillation, the condition during distillation, handling of the oil, storage, and storage conditions. Thus, the shelf life of an essential oil is hard to predict.

Though there is no perfect way to predict the shelf life an essential oil, the best practice is analyzing their chemical properties, which starts by knowing their chemical family.

The chemical families of an essential oil include the sesquiterpenes, sesquiterpenols, monoterpenes, monoterpenols, esters, ethers, aldehydes, ketones, phenols, and oxides.

1. Sesquiterpenes (8-10 years)

These are rich essential oils that are anti-bacterial, anti-fungal, analgesic, anti-spasmodic, anti-inflammatory, sedative, and cooling. These also tend to be energetically grounding, centering, and calming. So they have the base and middle notes. These include:

• Black Pepper
• Cedarwood
• Ylang Ylang
• Vetiver
• Spikenard
• Patchouli
• Opopanax
• Myrrh
• Ginger
• German Chamomile

2. Sesquiterpenols (10-15 years)

These oils have different therapeutic properties, but are usually anti-spasmodic, sedative, anti-inflammatory, anti-bacterial, skin healing, grounding, and immune stimulating. They have base notes and are heavier in terms of energy and emotional grounds. These include:

• Sandalwood

3. Monoterpenes (2-3 years)

These are airborne purifiers and deodorizers. They are also energetically and emotionally uplifting and can even give an analgesic effect to ease stiffness and muscle pain. They also minimize stagnation in energy as they support changes in the body. Since monoterpenes are unsaturated, they are usually unstable and more prone to oxidation.  These include:

• Lemon
• Sweet Orange
• Siberian Fir
• Rosemary
• Ravintsara
• Juniper Berry
• Grapefruit
• Frankincense
• Cypress
• Black Pepper
• Bergamot

4. Monoterpenols (5-6 years)

Monoterpenols are anti-infectious agents, so they are anti-spasmodic, anti-bacterial, antiviral and anti-fungal. Since they are non-toxic, they are mild on the skin and on the mucous membranes. These essential oils are usually used for skin care, nourishing the nervous system, supporting emotional balance, and strengthening the immune system. Monoterpenols include:

• Thyme
• Tea Tree
• Peppermint
• Palmarosa
• Rosewood
• Rose Absolute
• Lavender
• Geranium
• Basil

5. Esters (5-7 years)

These oils are antispasmodic and sedative. They are balancing, calming, uplifting, and soothing. So they are good for the digestive system and for the skin. Their aroma tends to be fruity or floral. Esters include:

• Wintergreen
• Roman Chamomile
• Helichrysum
• Jasmine Absolute
• Birch

6. Ethers (5-7 years)

These have the aroma of anise or licorice and tend to have antispasmodic, calming, and carminative. They can also reduce spasms and pain. However, they can be skin irritating. These include:

• Tarragon
• Nutmeg
• Fennel
• Anise 

7. Aldehydes (4-5 years)

Aldehydes have anti-inflammatory, sedative, anti-infectious, and antispasmodic properties so they are often used for cooling the temperature and toning the nervous system. They are also effective antifungal agents. If oxidized, these oils are irritating to one’s skin. These include:

• Melissa
• Lemongrass

8. Ketones (5-7 years)

These oils are usually used in aiding respiratory infections like flu and colds. They are effective mucolytics and expectorants, so they can relieve pain and reduce mucus. They are also analgesic. Ketones include:

• Thuja
• Spike Lavender
• Sage
• Pennyroyal
• Mugwort
• Hyssop
• Eucalyptus
• Clary Sage

9. Phenols (4-6 years)

Phenols are antiseptic, anti-bacterial, anti-infectious, rubefacient, and has disinfectant qualities. Usage over long periods of time will lead to toxicity, so you have to be careful in maintaining these oils. Phenols include:

• Clove bud

10. Oxides (3-5 years)

 Oxides are mucolytic, expectorant, and antiviral. It can aid any respiratory illness and also have stimulating effects on one’s mental processes. These include:

• Rosemary
• Laurel Leaf
• Eucalyptus

In Summary

Essential oils can have a shelf life of anywhere between 2-15 years. In and of themselves, they don’t deteriorate. However, once you start using them and exposing them to sunlight, oxygen and temperature changes, their chemistry will start to react to these elements and start becoming a “different oil” than when you first started using it. Being aware of this and cautious not to over-expose your essential oils to these factors, you can guarantee the most longevity of your precious essential oils.

What do you think?

What is your experience with long-lasting essential oils? Let me know in the comments below!