Essential Oils
<p>As the use of essential oils has declined in evidence-based medicine, one must consult older textbooks for much information on their use.<sup id="cite_ref-Sapeika_0-0" class="reference"><a href="http://en.wikipedia.org/wiki/Essential_oils#cite_note-Sapeika-0">[1]</a></sup><sup id="cite_ref-Thorpe1_1-0" class="reference"><a href="http://en.wikipedia.org/wiki/Essential_oils#cite_note-Thorpe1-1">[2]</a></sup> </p>
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Modern works are less inclined to generalize; rather than refer to "essential oils" as a class at all, they prefer to discuss specific compounds, such as <a href="http://en.wikipedia.org/wiki/Methyl_salicylate" title="Methyl salicylate">methyl salicylate</a>, rather than "oil of wintergreen".<sup id="cite_ref-isbn0-08-040296-8_2-0" class="reference"><a href="http://en.wikipedia.org/wiki/Essential_oils#cite_note-isbn0-08-040296-8-2">[3]</a></sup><sup id="cite_ref-isbn0-07-105239-9_3-0" class="reference"><a href="http://en.wikipedia.org/wiki/Essential_oils#cite_note-isbn0-07-105239-9-3">[4]</a></sup></p>
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An <b>essential oil</b> is a concentrated <a href="http://en.wikipedia.org/wiki/Hydrophobic" title="Hydrophobic" class="mw-redirect">hydrophobic</a> liquid containing volatile <a href="http://en.wikipedia.org/wiki/Aroma_compound" title="Aroma compound">aroma compounds</a> from plants. Essential oils are also known as <b>volatile oils</b>, <b>ethereal oils</b> or <b>aetherolea</b>, or simply as the "oil of" the plant from which they were extracted, such as <i>oil of clove</i>. An <a href="http://en.wikipedia.org/wiki/Oil" title="Oil">oil</a> is "essential" in the sense that it carries a distinctive scent, or essence, of the plant. </p>
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Essential oils do not form a distinctive category for any medical, pharmacological, or culinary purpose.</p>
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The potential danger of an essential oil is generally relative to its level or grade of purity. </p>
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Many essential oils are designed exclusively for their aroma-therapeutic quality; these essential oils generally should not be applied directly to the skin in their undiluted or "neat" form. </p>
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Some can cause severe irritation, provoke an allergic reaction and, over time, prove <a href="http://en.wikipedia.org/wiki/Hepatotoxic" title="Hepatotoxic" class="mw-redirect">hepatotoxic</a>. </p>
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Non-therapeutic grade essential oils are never recommended for topical or internal use. </p>
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Essential oils should not be used with animals, as they possess extreme hepatotoxicity and dermal toxicity for animals, especially for cats. </p>
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Instead, essential oils should be blended with a vegetable-based carrier oil (as a base, or "fixed" oil) before being applied. Common carrier oils include olive, almond, hazelnut and grapeseed. </p>
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Only neutral oils should be used. </p>
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A common ratio of essential oil disbursed in a carrier oil is 0.5–3% (most under 10%), depending on its purpose. </p>
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Some essential oils, including many of the <a href="http://en.wikipedia.org/wiki/Citrus" title="Citrus">citrus</a> peel oils, are <a href="http://en.wikipedia.org/wiki/Photosensitivity_in_humans" title="Photosensitivity in humans">photosensitizers</a>, increasing the skin's vulnerability to sunlight. </p>
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Industrial users of essential oils should consult the <a href="http://en.wikipedia.org/wiki/Material_safety_data_sheet" title="Material safety data sheet">material safety data sheets</a> (MSDS) to determine the hazards and handling requirements of particular oils. </p>
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Even certain therapeutic grade oils can pose potential threats to individuals with epilepsy, or pregnant women.</p>