Why Do Essential Oil Aromas Change?

by Erin Sweeney October 05, 2021

Why Do Essential Oil Aromas Change?

Each essential oil comes with a beautiful and unique aroma profile. Most people are able to pick up on the different nuances of oils and enjoy their complexities and some sensitive noses may be able to identify tiny differences between oils.  

Whether it be opening a new bottle that doesn’t quite smell the same as the last one you purchased or reopening an old bottle that smells different from when you first opened it, aromas change for a variety of reasons. And in this guide, we’ll be exploring those reasons and answering your questions on changing aromas. Read on to find out more about this fluid situation. 

Why Do Essential Oil Aromas Change?

When you notice an aroma change, you may want to jump to the conclusion that something is wrong with the oil or that it has expired. While this may be the case some of the time, it can most often be a result of one of the following.

Batch To Batch

Perhaps you’ve been purchasing the same oil for a while. Then one day you receive a new bottle and notice that its aroma is vastly different from previous oils you’ve purchased. What does this mean? 

There are a few possibilities here, but the most common one is that oils are natural products that come from plants that are affected by a variety of factors. These factors include rainfall, water levels, pH of soil, altitude, sunlight and more. Each factor can change the natural chemistry of a plant, thus altering its aroma, as well as the aroma of the essential oil that’s obtained from it. 

So when you receive an oil from a new batch, you might pick up on a few differences in aroma. Because at Edens Garden, we do not alter our oils to be consistent with every batch so that we may keep each oil’s purity and quality intact. 

How You Use Your Oil

If you’ve ever noticed a change in an oil’s aroma when you smell it straight out of the bottle, versus when you use it on your skin or diffuse it, you know that how you use an oil can affect its aroma. But why is this? 

Smelling an oil straight out of the bottle or on an essential oil scent strip is possibly the best way to get a true sense of an essential oil’s aroma because once you add it to an essential oil diffuser or use it topically with a carrier oil, the oil changes with the water or individual’s chemistry. Note here that our essential oils and perfumes will smell different on every individual because each person’s chemistry is unique.

Over Time

Time changes all things and essential oils are no exception. Oxidation, or oxygen interacting with your oil, can alter its aroma over time. The oxidation process occurs when you open and close your bottle, allowing oxygen to enter in. It can also occur as your oil level begins to drop, and you're left with a ‘head space’ of air in the bottle.

Other factors that can cause your oil’s aroma to change with time include frequent light and heat exposure. 

On the flip side, certain essential oils have aromas that get better with age. These are generally the oils that have naturally heavier molecules, such as Sandalwood, Patchouli, Vetiver and Buddha Wood

Has My Essential Oil Expired?

While a change in aroma is likely caused by one of the factors we’ve discussed, it could also mean that your oil has expired. 

Some essential oils expire faster than others because they are more prone to oxidation, such as citrus essential oils, while others have heavier molecules that allow them to be more stable, like wood oils. 

Here are a few ways to decipher whether your oil has gone bad:


If an essential oil is not as pungent, crisp or fresh as it once was, and if it has a stale or rancid odor, this may be a sign that the oil has oxidized. 

Oil Appearance 

Some essential oils, particularly any type of citrus oil, separate and grow cloudy as the compounds go through oxidation. Be sure to check out the color and clarity of the oil through the glass bottle when you first get it–this will allow you to better observe changes over time. 

Check The Essential Oil Bottle or Product Page 

At Edens Garden, every single one of our essential oils and blends has a section on their product page devoted to “Safety and Shelf Life.” Confer with this page so you know the expected shelf life. Compare that number with the date you purchased the product online. If you’re unsure when you purchased your product, you can contact our customer care team and they will look up your past orders. 

If you notice a change in the oil’s aroma and appearance, it may be safe to assume that your oil has expired. Once your oil expires, you can still use it for its aroma in DIYs and even in an ultrasonic diffuser, if you believe its aroma is still enjoyable. However, expired oils can no longer be used in therapeutic aromatherapy and should not be used topically. 

Keeping Your Oils Fresh

While you may not be able to keep an oil’s aroma consistent if its aroma has changed with a new batch or with each different use, you can prevent your oils from changing over time with these tips. 

Store It Properly 

Proper essential oil storage simply comes down to keeping the bottle sealed when not in use. The less exposure they have to oxygen, the longer they’ll last. 

Keep It At The Right Temperature  

You can maximize your oils’ shelf life by storing them in the refrigerator with little light exposure. However if you do put them in the fridge, be sure to double bag your oils or put them in a container, otherwise they can affect the flavor of any surrounding food. 

Use Smaller Containers 

To prevent oxygen from interacting with your oils, you may continuously move oils to smaller containers to keep oxygen out. For example, when you use half of a 10 ml bottle, transfer the rest of the oil to a smaller bottle, such as a 5 ml bottle, to keep out as much oxygen as possible. You can also fill a bottle with glass marbles to decrease the bottle’s headspace. This is not necessary but suggested if you wish to extend the shelf life of your oils that are prone to oxidation, like those mentioned above.


  1. When Does Perfume Actually Expire? We Investigate. https://www.byrdie.com/how-long-does-perfume-last-4768465

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1 comment

Jessica Parshall

October 6, 2021 at 1:53 pm

I found this article to be extremely useful. Over half of my oil collection is at or past the “shelf life” listing and all but a few have had scent changes, one has had a change in appearance but none smelt spoiled or rancid. This helps me understand more and make more informed choices about those oils.