How long do essential oils keep after opening?

This week a question came in from my community that is so practical the answer deserves a permanent spot on the site: how long can you keep using an essential oil once the bottle has been opened? There is a date on the bottom of your bottle, but it only tells half the story. So this page is made to be kept, and to be forwarded to anyone with a cupboard full of bottles.

What the date under the bottle means

The date under your bottle is the manufacturer’s best-before date, counted from the production date. It applies to an unopened, well-stored bottle, and it has nothing to do with the moment you first twist off the cap.

From that first moment, a little oxygen reaches the oil every time, and oxygen slowly changes the composition: that is oxidation. You won’t find a separate after-opening period on the bottle or in the product information; for that you need the professional literature. The standard reference is “Essential Oil Safety” by Robert Tisserand and Rodney Young, and that is where the rules of thumb below come from.

Three groups, three timeframes

And blends? A blend follows its most delicate ingredient. If there is citrus in it, as in Citrus Bliss, the citrus rule applies; for the rest, go by the middle group.

And the Touch rollers? They are a story of their own. A roller runs straight over your skin, often even under your feet, and with every roll it picks up skin cells and bacteria that travel back into the bottle. On top of that, the oil in it is diluted in coconut oil, and that dilution protects itself less well than a neat oil. So with a Touch you have been using, think in months rather than years, and trust your nose all the more: if the smell or the look changes, it is done.

What really ages an oil

An oil ages through four things: oxygen, light, heat and big swings in temperature. Nothing ages an oil faster than oxygen, and it gets in every moment the cap is off. That is why your oil comes in dark glass, and why the most important storage tip is also the simplest one: cap back on straight away.

Beyond that: keep your bottles in a dark cupboard, because the bathroom with its warm shower air is the worst spot in the house. Don’t leave oils in the car in summer; one afternoon in the sun is a round-the-world trip for an oil. Citrus is welcome in the fridge, and if the oil turns thick or cloudy in there, it settles again at room temperature. And a nearly empty bottle is mostly a bottle full of oxygen: pour the rest into a small amber bottle and the oxidation slows right down.

How to tell when an oil is no longer good

Your nose is your best instrument. Fresh citrus oil smells zesty; an oxidised oil smells dull, flat or slightly resinous. You no longer want that bottle on your skin, as oxidised oil can irritate more readily. No need to bin it straight away: for your homemade cleaning spray or a few drops in the laundry that oil is often still fine.