Dr.'s Blog

Essential oils are immeasurably powerful in their impacts on our body and mind.

Which is why we want to maintain optimal potency to get the maximum benefits from our oils!

Research supports the idea that heat can degrade or diminish the potency and efficacy of essential oils. Essential oils are composed of volatile compounds that can be sensitive to high temperatures. When exposed to heat, these compounds can evaporate, oxidize, or break down, leading to a reduction in their therapeutic benefits and aroma. Here’s a deeper look at the impact of heat on essential oils:

1. Volatility of Essential Oils

Essential oils are composed of small, volatile molecules that readily evaporate at room temperature. When subjected to high heat (often above 80°C or 176°F), many of the delicate compounds in essential oils, such as terpenes, aldehydes, and phenols, can degrade. This results in a loss of potency and the chemical structure of the oil changes, which can diminish both its therapeutic properties and aroma.

Supporting Study:

• A study published in the Journal of Food Science and Technology demonstrated that thermal degradation is a significant factor in the breakdown of bioactive compounds in essential oils. Prolonged exposure to temperatures above certain thresholds led to oxidation and reduced efficacy of oils, particularly affecting the antimicrobial and antioxidant activities .

2. Oxidation

Heat accelerates the oxidation process of essential oils. Oxidation occurs when oxygen reacts with certain components, like monoterpenes, leading to chemical changes. These reactions can make the oils less effective and, in some cases, even increase skin sensitivity or irritation when applied topically.

Study Example:

• According to research from the International Journal of Molecular Sciences, oxidized components, especially in oils like citrus oils, lose their potency and can become more irritating to the skin when exposed to heat and air .

3. Effect on Therapeutic Properties

Heat can also reduce the antimicrobial and anti-inflammatory properties of essential oils. For example, oils like tea tree and lavender are valued for their antibacterial and calming effects, but heat can diminish these properties by breaking down the active compounds responsible for their efficacy.

Study Insight:

• A study in Planta Medica found that essential oils like oregano and thyme, which are rich in phenolic compounds (e.g., carvacrol and thymol), lose a significant amount of their antimicrobial activity after being heated beyond certain thresholds .

4. Citrus Oils and Heat Sensitivity

Citrus oils, such as lemon, orange, and bergamot, are particularly sensitive to heat. Their high concentration of limonene (a monoterpene) makes them prone to oxidation when exposed to light and heat, reducing their effectiveness and making them more susceptible to degradation.

Study Insight:

• Research published in Food Chemistry confirms that heat exposure decreases the antioxidant properties of citrus essential oils, largely due to the breakdown of limonene .

Conclusion: Best Practices for Preserving Essential Oils

To maintain the potency and efficacy of essential oils:

• Avoid high heat: Store oils in a cool, dark place away from heat sources.
• Proper storage: Use dark-colored glass bottles to minimize light exposure, as light can also contribute to oxidation.
• Avoid heat diffusion methods: If diffusing essential oils, opt for cold diffusion or ultrasonic diffusers, as these use water and ultrasonic waves rather than heat, preserving the oil’s properties.

Best Practices for Maximum Potency

To retain as much potency and benefit of essential oils, following these best practices will help minimize degradation and preserve the therapeutic properties:

1. Store in Dark, Glass Containers

• Essential oils are highly sensitive to light, especially UV rays, which can degrade the volatile compounds. Dark-colored amber or cobalt blue glass bottles are ideal for minimizing light exposure and preventing oxidation.
• Avoid plastic containers, as essential oils can react with plastic, leading to contamination.

2. Keep in a Cool, Dry Place

• Heat accelerates the breakdown of essential oils. Store oils in a cool, dry place, ideally below room temperature. Consider a refrigerator for long-term storage of sensitive oils like citrus oils.

3. Tightly Sealed Caps

• Exposure to air can cause oxidation, which diminishes the oil’s potency over time. Make sure bottles are tightly sealed after every use to limit oxygen exposure.

4. Avoid Heat Diffusers

• Heat diffusers can degrade essential oils by breaking down their volatile compounds. Opt for ultrasonic diffusers, which use cool water and vibrations to disperse oils without heat, preserving their therapeutic qualities.

5. Dilution with Carrier Oils

• When applying essential oils topically, diluting them with carrier oils like jojoba, coconut, or almond oil can help retain the oils’ benefits, reduce evaporation, and prevent skin sensitivity. This also allows for more even application and absorption.

6. Limit Direct Sunlight

• Exposure to direct sunlight can degrade essential oils. If you’re blending oils or using them on the skin, avoid applying them right before going out into strong sunlight. Certain oils, like citrus oils, can cause photosensitivity, leading to skin irritation or burns when exposed to UV rays.

7. Use within Recommended Timeframe

• Essential oils don’t last forever. Over time, their chemical compositions can change, reducing their effectiveness. Most oils retain their potency for 1–3 years, but oils like citrus oils have a shorter shelf life. Woodsy oils like cedarwood or sandalwood can last longer (up to 5 years or more).

8. Avoid Contaminants

• Don’t touch the dropper or cap with your fingers, as this can introduce bacteria and degrade the oil faster. Use clean, dry tools to handle your oils.

9. Mix with Low Heat

• If you must mix essential oils into heated preparations, such as candles or lotions, do so at low temperatures to minimize the risk of losing volatile compounds. Ideally, add oils after the product has slightly cooled to retain their potency.

10. Be Aware of Photosensitivity

• Some oils, particularly citrus oils like lemon, lime, and bergamot, can make your skin more sensitive to sunlight. To avoid skin reactions, don’t apply them before exposure to direct sunlight, or dilute them well.