Oil Stability

In Lesson 4, you’ll learn about the stability of essential oils and carrier oils, how to recognize when oils begin to oxidize, and how to store them for optimal freshness and safety. We’ll also look at how aroma, note classification, and oil type influence an oil’s longevity, and how proper storage practices can help extend the life of your favorite oils.

Labels describe an oil’s aroma and list whether it’s considered a top, middle, or base note in perfumery and blending. This helps you to more accurately use the oil when blending and formulating home products, and to create synergistic or aromatically balanced blends. As oils age, your sense of smell is one of the first clues that something has changed. An oil that once smelled bright and fresh may begin to smell flat or stale. This can indicate oxidation and may mean it's time to replace the oil, especially if you plan to use it topically.

When oils oxidize, they don’t go bad overnight. It’s a slow process and doesn’t immediately negate their health benefits. Some oils, when exposed to heat and light, go through certain chemical reactions or changes. When this happens, some of the constituents may become more irritating, while others may lose their effect. For this reason, it’s best not to use oils topically that are significantly past their average shelf life.

Top note oils tend to oxidize more readily than middle or base note oils. Most top note oils, like citrus, have an estimated shelf life of approximately 2 years under normal conditions. Top note oils are often the first part of a blend you will notice, like lemon or peppermint.

They give refreshing and uplifting characteristics to blends. To preserve their shelf lives, store them in cool, dark places, with their caps fastened.

Middle note oils are more stable. Common middle notes include lavender, rosemary, and geranium. They form the heart of most blends and are often some of the most complex oils, containing sometimes hundreds of chemical constituents.

 Their balanced volatility means they tend to shift slowly, making them a reliable choice for long-lasting blends. They still need to be stored with care in a cool, dark place to maintain balance and aroma.

In general, base note oils tend to oxidize slowly, making them the most stable and long-lasting. For certain oils, the top notes in an oil naturally fade and the true heart of a base note emerges, giving aged oils a richer and smoother scent. 

Many aromatherapists intentionally keep bottles of patchouli or sandalwood around for years, so that they can enjoy the aromatic aging process like one would a fine wine.

Carrier oils don’t dissipate, but they do oxidize, some faster than others. A rancid aroma is a key indicator of oxidization. Many carrier oils have an estimated shelf life of 2–5 years, with a couple of notable exceptions. Jojoba doesn’t really oxidize since it’s a liquid wax, so its shelf life can be measured in decades. Rosehip, on the other hand, oxidizes very easily and should always be stored in a cool, dark place.

If you're blending your essential oils for topical use, your blend's shelf life doesn't just depend on the essential oil — it also depends on the carrier oil you choose.

Absorbent, liquid wax that
resembles the skin’s pH factor and
natural emolliating processes of
sebum production. Commonly used
in facial care and ideally suited to
all skin types because it does not
clog pores. Expeller pressed from
the seeds of the jojoba plant.

Shelf Life: Indefinite (up to 10+ years)

Jojoba is technically a liquid wax, so it resists oxidation and does not go rancid like true oils.

Cold pressed from the seeds of organic tropical castor plants. Commonly used as a cleansing element in targeted skin care routines. Contains essential fatty acids known for moisturizing and maintaining the balance of the skin.

Shelf Life: 1–2 years

Naturally thick and stable, but it should still be kept tightly capped and out of sunlight.

Rich, skin-rejuvenating oil is 
frequently used to care for aging
skin. Contains essential fatty
acids known for their moisturizing
properties and has a heavier
consistency. Expeller pressed
from ripe avocados.

Shelf Life: 1 year

Rich in nutrients but prone to oxidation. Refrigeration can help extend its life.

Light, quick-absorbing oil expeller
pressed from ripe apricot seed
kernels. Contains skin-nourishing
essential fatty acids that help
maintain moisture balance, making
it great for everyday care.

Shelf Life: 1–1.5 years

Light and fast-absorbing, but slightly more delicate. Store in a cool, dark area.

Lightweight, fast-absorbing oil
great for everyday care. Full of
antioxidants that rejuvenate dry
skin and hair. Obtained through
distillation, when a fraction of
the oil emerges as a liquid.

Shelf Life: Up to 5 years 

This form of coconut oil does not solidify and has excellent oxidative stability.

Expeller pressed from ripe almonds
and high in moisturizing essential fatty
acids. Its weight and nutrient density
make it great for everyday care, such
as bath and after-shower applications,
and especially appropriate for caring
of dry skin.

Shelf Life: 1–2 years

A versatile, gentle oil that keeps well under proper storage but will oxidize over time.