The Safe Use of Essential Oils

In general, when used properly essential oils are quite safe and highly beneficial. However, because their uses are still relatively unknown, people can and do hurt themselves by using these highly concentrated botanical substances improperly.

Toxicology And Safety


The first exception to the rule is if it’s properly administered dose prescribed by a licensed physician. European clinics prescribe essential oils, but are rarely available in the US.

You should avoid using essential oils internally if prescribed by any kind of lay practitioner, especially if the practitioner’s education is primarily from the marketing perspective rather than clinical.

The second exception to the no-ingestion rule is when you’re ingesting biocompatible levels of essential oil ingestion as part of a diet. A good example of this is oregano oil, widely marketed for internal consumption, with numerous claims about its therapeutic efficacy.

In practice, the internal consumption of oregano oil frequently causes symptoms associated with the ingestion of essential oils — including extreme gastric hyperacidity. On the other hand, the use of oregano as a fresh herb, steamed at the end of food preparation, provides all the benefits of oregano oil at a biocompatible level with none of the gastric dangers.


Essential oils are very concentrated. Dilute all essential oils before applying to the skin, either in a fatty oil or in water as when used on a compress.

There are two exceptions to this rule:

The first is the use of attars as natural perfumes. Because the floral essences are distilled into a base of sandalwood oil, the sandalwood oil acts as a carrier, which dilutes the potency of the pure essential oil.

The second is the reasonable use of mild essential oils that have a well-documented history of safety. The best example of this is lavender — however, even lavender can be problematic for some people.


Skin reactivity issues are on the rise as synthetic aroma chemicals become common adulterants in the essential oil industry.

A general rule is to never apply more than one to two drops of undiluted oil to the skin. Especially if you have sensitive skin, always test a small area with a diluted oil before applying over a larger area.

For general non-medical use, avoid essential oils with highly sensitive skin and with any instances of skin allergies, severe inflammationand dermatitis. Pure essential oils are much less dangerous than synthetic aroma chemicals.

Skin reactions vary depending on the type of oil, concentration, and the condition of your skin. If you’re using them with clients, be sure to ask about any history of skin reactions before using oils  either for dermal or respiratory applications. Old and oxidized oils are more prone to cause reactions, especially rashes.

Refrigerate fatty carrier oils to prevent rancidity. Essential oils generally have a shelf life of one to three years. Some get better with age, such as sandalwood oil, vetiver oil, and patchouli oil. Meanwhile, citrus oils are most prone to degradation and should be used within one year.

Skin reactions to essential oils can take three forms:

  • Irritation. A small number of oils can be severely irritating, including horseradish, mustard, garlic, and onion (which are rarely used in aromatherapy practice). Some oils used in massage practice can be moderate irritants, such as cinnamon bark oil, clove, fennel, and verbena.
  • Sensitization. Skin sensitization is a term for allergic skin reaction — this usually manifests as a rash. There aren't many oils used in a typical massage practice that will produce sensitization under normal applications in a carrier oil. However, there are a number of reports on Pubmed of allergic reactions to essential oils, including contact dermatitis, eczema, asthma, and pruritic erythematous eruptions. These reactions were mostly found in practitioners who use essential oils professionally for long periods of time, such as massage therapists and estheticians.
  • Phototoxicity. Some essential oils can strongly increase sensitivity to sunlight when applied to the skin. This is especially dangerous when applied undiluted to the skin, but even low concentrations in a carrier oil can cause problems if followed by exposure to sun or tanning lamps. Phototoxicity is much stronger directly after application of the oil and will gradually decrease over an eight to twelve hour period. Most of the phototoxic oils are also photocarcinogenic. The most common oils that cause phototoxicity are the citruses; bergamot oil is the most reactive. Some citruses are phototoxic if expressed, but not if distilled, such as lemon oil and lime oil. Other oils include marigold oil (tagetes), verbena, and angelica oil.

Be sure to use proper dilutions, avoid direct exposure to UV rays after application, and avoid the use of citrus oils if you’ll be spending time in the sun after treatment.


Measurements/conversions (by volume)

30 mL = 1 fl oz = 600 drops = 2 tablespoons

15 mL = ½ fl oz = 300 drops = 1 tablespoon

5 mL = ⅙ fl oz = 100 drops = 1 teaspoon

1 mL = 1/30 fl oz = 20 drops = ⅕ teaspoon



For one fluid (1 oz) ounce of Carrier Oil:

1% of 600 drops (1 fl oz) = 6 drops

2% of 600 drops (1 fl oz) = 12 drops

2.5% of 600 drops (1 fl oz) = 15 drops

5% of 600 drops (1 fl oz) = 30 drops

10% of 600 drops (1 fl oz) = 60 drops 

The best treatment for skin irritation from essential oils is to apply a fatty oil, such as coconut, to dilute the oils’ impact. Avoid contact with eyes and mucous membranes. If an essential oil gets into the eye, do not rub it. Saturate a cotton ball with milk or vegetable oil and wipe over the area affected. In severe instances, flood the eye area with lukewarm water for fifteen minutes.


Take special precautions with applications near delicate skin areas.

Use only pure essential oils; avoid synthetic fragrances. Avoid prolonged exposure without ventilation.

Overexposure to essential oils, especially in confined areas, can cause dizziness, nausea, lightheadedness, headache, blood sugar imbalances, irritability, euphoria.

When exposed to high levels of essential oils make sure to keep the room well-ventilated.

Store essential oils and carrier oils properly to avoid degradation and rancidity.

Air, heat and light degrade essential oils.

Store essential oils in a cool, dark room and always keep your oils tightly sealed.

Do not use essential oils on infants, children, pregnant women, the elderly, or those with serious health problems, without advanced medical study.

Before experimenting with an oil, become familiar with its properties, dose, and precautions.

When in doubt about a condition or an oil, consult a qualified medical specialist.


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