Do Essential Oils Go Bad?

If you've ever found forgotten leftovers you know that over time things spoil. Cooking or salad oils can go rancid. But what about essential oils? Do they ever smell rancid or bad? Do they spoil in time? Do they have a shelf life or do they last forever?

The short answer is no, essential oils don't spoil or go rancid. So if you've ever had an essential oil that smells rancid, chances are it wasn't 100% pure essential oil and likely diluted with carrier oil.

However, essential oils can oxidize and oxidized essential oils can cause irritation to skin when diffused. And even though oxidation might not affect the color or smell of an oil it affects the oil's properties.

The rate at which oils oxidize depends on their chemistry and how the oils are stored.

Light, heat, and oxygen can increase the rate of oxidation.

So for the best shelf life oils should be stored in dark, cool, places, and tightly capped. Understanding shelf life of essential oils technically does require a bit of chemical knowledge.

Oils that are rich in monoterpene or smaller unsaturated molecules tend to oxidize more rapidly than oils that contain heavier, molecules. So in general for example a d-limonene ( monoterpene) rich citrus oils tend to last only 1 or at most two year before they begin to oxidize, while thicker oils such as cedarwood or patchouli can last six to eight years. Oxidation depends on the chemical stability of the aromatic compounds in given essential oil. Based on oil chemistry and proper storage:

Monoterpene rich oils: last 1 to 3 years Monoterpenol rich oils: last 3 to 5 years Sesquiterpene rich oils: last 6 to 8 plus years Sequiterpenol rich oils: last 6 to 8 plus years Phenol rich oils: last 3 to 5 years Aldehyde rich oils: last 2 years Ketone rich oils: last 3 to 5 years Ester rich oils: last 3 to 5 years Ether rich oils: last 3 to 5 years Oxide rich oils: last 2 to 3 years

Can you use an oil once it is oxidized? Yes and no. If an oil is oxidized it is NOT a good idea to use it topically.

Instead many opt to use oxidized oils for cleaning products.

Often there is no detectible odor or color difference, but there is an increased risk of skin or mucus membrane irritation. If a citrus oil is more that a year or two oil it's best to use it for cleaning rather than blend it into bath or skin products.

So in summary essential oils don't exactly go bad but they can oxidize. And oxidized oils can cause irritation and are better suited to cleaning than topical application or diffusion. The bottom line if you purchase oils use them! It took a lot of plant material, time, and effort to produce the oil. Cherish and use it. Have questions about aromatherapy or essential oils? contact Tricia.

Aromatic blessing my friends,

Tricia