Since plant proteins are removed during the essential oil distillation process one might assume you cannot have an allergic reaction to essential oils. However skin sensitization, irritation, and photosensitivity to topically applied oils has been observed in even the mildest of essential oils. Diluting essential generally reduces the risk of this occurring. However, an allergen can be defined as "any protein or non-protein capable of producing an allergic reaction or specific hypersensitivity".1 Essential oil constitutes may bind to proteins in the skin, the complex may migrate to local lymph nodes and prime the immune system to recognize the oil-protein complex as a threat and result in an allergic reaction. Lets look at the three basic issues that can affect the skin:
1. Irritation: (also called irritant contact dermatitis (ICD) or contact urticaria)
2. Sensitization: (also called allergic contact dermatitis (ACD) or allergic urticaria)
3. Photosensitivity: (also called photosensitization and phototoxic contact dermatitis)
Irritation: A localized reaction to where the product was applied that is dose dependent. The higher the dose, the worse the reaction. The signs may be delayed but often are immediate and acute and occur on the first exposure.
* What happens: Red irritated, itchy, skin. Dryness or blistering may occur.
* How to avoid: Use less essential oil or a lower dilution. Oils that are high in phenols, aldehydes and monoterpenes are often responsible (strong, spicy, or citrus oils). Use these oils in lower dilutions. Don't use oxidized oils, and dilute oils for those who are sensitive.
* Good idea to test diluted oils/blend on small patch of skin.
Sensitization: Sensitization is an allergic reaction of the immune system. The reaction will be noticed in places other than where you applied the oil. This reaction often occurs on first use of oil but may be unnoticeable. With subsequent use a more intense reaction may occur. The intensity of the reaction may seem out of proportion to the amount of oil used.
*What happens: Rash with raised, itchy bumpy skin, possible headache.
*How to avoid: Don't use oils, oxidized oils. Aldehyde and lactone rich oils are likely to be sensitizers. Avoid or dilute these oils.
* Patch test on forearm
* If someone knows they are sensitive to certain aromas, avoid or use in very low dilutions.
Sensitization is not clear cut. As components such as linalol and geraniol are so widely used in the fragrance and cosmetic industry, they have a wide public exposure. It's possible that people can become sensitized to these components and thus react to so-called 'safe' oils like Geranium and Lavender. A substance can be non-sensitizing initially, but through metabolism and subsequent transformation within the skin, it can become sensitizing. Heat and humidity increase skin absorption, so skin reactions are more common in tropical climates. Sensitization is not necessarily related to dose and may take several exposures to occur. Only about 1% of the population has fragrance allergies. Women are more likely than men to experience this and the greatest areas of risk are the face and hands.
*Diluting oils properly or using a very low dose may help reduce the risk of sensitization.
Photosensitivity: Phototoxicity is a UV induced reaction to a photoactive substance. It required both contact with the offending substance and UV exposure. Essential Oil phototoxicity occurs upon exposure to sunlight or UV radiation, which can cause burning, blistering, and discoloration. The most common phototoxic agents are furocoumarins. These molecules absorb UV radiation from the sun or tanning beds and release it in a burst into the skin. Variables are dose, amount of time between application and sun exposure, and dilution. A quick walk from the house to the car is fine but a long stroll on the beach or working in the garden increases your risk. Blending several phototoxic oils together increases the risk.
* What happens: exaggerated sunburn and blisters. Reddening, swelling, and change in pigmentation. This can be very painful.
* Common phototoxic oils: When cold pressed Bergamot, Lime, Bitter Orange, Lemon, Grapefruit. Not all citrus oils are phototoxic. When distilled many also no longer be of concern. For example, these citrus oils do not cause photosensitization: Lime (distilled), Lemon (distilled), Sweet Orange (cold pressed), Mandarin (cold pressed), Tangelo (cold pressed), Tangerine (cold pressed). It's best to check the bottle and product information to be sure of what's in your bottle.
* How to avoid: Avoid sunlight or UV exposure for recommended amount of time. Apply diluted oils to areas that will be covered by clothing. Use oils safely:
Bergamot: 1 drop per 1 ounce (30 ml) of carrier
Lime (cold pressed): 4 drops per 1 ounce (30 ml)
Bitter Orange (cold pressed): 8 drops per 1 ounce (30 ml)
Lemon (cold pressed): 12 drops per 1 ounce (30 ml)
Grapefruit (cold pressed): 24 drops per 1 ounce (30 ml)
You need not fear using these beneficial oils, just use them properly and with respect.
In summary essential oils are an amazing tool to support health and wellness but they can in some instances cause skin irritation when used topically. Patch testing, diluting oils, and attention when using phototoxic oils can help one lessen the risk of such reactions. Care should be taken with those who have seasonal or skin allergies and asthma. You can have a person sniff the cap of an essential oil and note the effect it has on their breathing or tightness in their chest. If the oil seems to impede their breathing it is wise to avoid using that oil and substitute another. All in all aromatherapy is a delightful way to enjoy the benefits of essential oils and their ability to support immune health, moods, sleep, and overall health and wellness. However with the growing popularity of essential oils it is important the users understand how to choose high quality oils and use them properly.
(2) "Three Concerns for Skin" Aromatherapy Certification Program Lesson 1 Part 3 Black and Butje
(3) "Essential Oil Safety" Tisserand and Young