An Overview of Essential Oils

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Essential oils are highly concentrated plant extracts distilled into oil. Popular in complementary and alternative medicine, these oils, derived from flowers, leaves, roots, and other parts of plants, have been used for medicinal purposes in some cultures for centuries.

Continuing scientific research has found that certain essential oils do indeed have health benefits; in fact, many modern medications are derived from essential oils. However, while some oils are beneficial in small doses, others can be dangerous.

Because essential oils are not regulated by the U.S. Food and Drug Administration (FDA), most should be used with caution, ideally with the guidance of a certified holistic practitioner.

essential oil
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Essential oils are often used to ease stress, boost mood, relieve pain from headaches and migraines, get a better night's sleep, quell nausea, and even repel insects. Most essential oils have antiseptic properties as well.

The beneficial compounds in oils often are delivered in three ways—inhalation, topical application to the skin, and oral ingestion.


Essential oils typically are extracted using steam distillation, a process that involves applying steam to a plant until only oil remains. Essential oils contain volatile compounds, which make up the strong characteristic scent of a plant and give them their therapeutic effects.

In aromatherapy, these volatile compounds are inhaled using either a drop of oil on a piece of cloth, jewelry, or other item, or diffused into the air with an aromatherapy diffuser. Inhalation is the safest method for using essential oils.

When inhaled, molecules in essential oils are believed to influence the nervous system and the limbic area of the brain, as well as hormones, brain chemicals, and metabolism.


Essential oils sometimes are applied directly to the skin to treat pain in a specific body part—to relieve backache, for example, or to ease sore muscles, or to relieve sinus pain—and some may be used topically for their antiseptic and anti-inflammatory properties, such as for acne or fungal infections.

However, many essential oils can be irritating and so should not be applied full-strength to the skin but rather diluted in a carrier oil (such as almond, apricot kernel, or avocado oil) first. 

Essential Oils That Irritate Skin

These should never be applied directly to skin unless properly diluted:

  • Bay
  • Cinnamon
  • Clove
  • Citronella
  • Lemongrass
  • Oregano
  • Thyme

Always test essential oils on a small patch of skin before applying to a larger area.

Essential oils also sometimes are added to soap, lotion, shampoo, bath salts, and other products, and used during massage and spa treatments.


Some essential oils can be used in cooking or even swallowed in small doses as medication, but this should be done with great caution. While many are safe in small doses, others are inherently poisonous and should never be ingested.

The potential risk of ingesting essential oils is heightened by the fact that they are not regulated by the FDA and there are no universal standards for ensuring the quality of the oil.

The National Association of Holistic Aromatherapy (NAHA) recommends purchasing oils from a reputable supplier who analyzes its products and tests them for purity using gas chromatography-mass spectrometry (GC-MS).

Essential oils should only be ingested with the guidance of a qualified essential oil therapist, and dosed and diluted appropriately for safety. Because essential oils are fat-soluble, it's important to eat some sort of dietary fat at the same time they're taken.

Health Benefits

Essential oils can be used to treat many physical and emotional health issues. At the molecular level, these oils contain beneficial compounds like antioxidants, terpenes, and esters that may help to boost wellness.

Although the body of research showing potential health benefits of essential oils is growing, many studies are limited to testing on animals and cell cultures. Large-scale human clinical trials looking at the effects of individual oils on specific health conditions are lacking.

But at least one study published in the Journal of Dietary Supplements was promising. It evaluated the general health effects of supplements, herbs, and essential oils and found oils are as effective as other supplements in improving health.

In particular, study participants reported improved immunity, reduced pain and anxiety, and enhanced energy and mental clarity. Laboratory tests also found improved blood markers associated with cholesterol, diabetes, and heart disease.

Common Oils

There are dozens of essential oils, each with a unique scent and potential healing properties.

  • Basil: Distilled from the popular cooking herb, basil oil is believed to ease coughs and congestion, enhance mood, improve digestion, increase alertness, and soothe muscle aches.
  • Bergamot: This citrus oil gives Earl Grey tea its distinctive flavor and is used to relieve anxiety. Bergamot also is being studied for its potential to lower cholesterol.
  • Calendula: A relative of the marigold, calendula may soothe rashes, wounds, yeast infections, and other skin irritations.
  • Carrot seed: Used in cosmetics, this oil has antibacterial and anti-inflammatory properties.
  • Cedarwood: Used to treat hair loss, cedar or cedarwood oil may also ease stress and improve sleep.
  • Cinnamon: Research suggests the oil in this popular spice may improve circulation, relieve stress, ease pain, fight off infections, and improve digestion.
  • Citronella: A natural insect repellant, citronella also may relieve stress and fatigue.
  • Clove: Spicy clove oil can be used to treat toothaches and other types of pain.
  • Eucalyptus: The active ingredient in VapoRub, eucalyptus is commonly used to treat colds, congestion, and coughs, and is being studied for antibacterial benefits.
  • Frankincense: This Biblical oil can help treat dry skin and reduce the appearance of wrinkles, age spots, scars, and stretch marks. It is also being investigated as an anti-cancer agent.
  • Geranium: Commonly used in skincare, research shows this floral oil has antimicrobial properties.
  • Grapefruit: This citrus oil is said to relieve hangovers and jet lag and is used to reduce stress, stimulate circulation, increase energy, enhance mood, and improve digestion.
  • Helichrysum: This oil has a medicinal scent and is often used to reduce inflammation, promote healing of wounds and burns, stimulate digestion, boost the immune system, and soothe body and mind.
  • Jasmine: A sweet-smelling floral oil, jasmine is touted as a stress-reliever with the potential to help treat dry skin and signs of aging, inflammation, and psoriasis.
  • Lavender: One of the most widely used essential oils, lavender is used for relaxation and to relieve insomnia.
  • Lemon: Said to boost mood and energy, this citrus oil relieves anxiety and may help promote weight loss.
  • Lemongrass: Used for stress-relief and to help boost immunity, studies suggest this oil can treat dandruff and fungal infections, and ease anxiety, headaches, and upset stomach. 
  • Myrrh: Myrrh is believed to ease coughs and colds, soothe digestive discomfort, and boost immunity.
  • Neem: Neem is used to treat nail fungus and acne. It also is an effective insect repellent.
  • Neroli: This sweet oil is used to relieve anxiety and may lower blood pressure.
  • Orange: The bright citrus scent of orange can boost energy and improve mood. There's also research to suggest it can ease anxiety.
  • Patchouli: This musky scent, popular in incense, has been found to improve sleep in studies.
  • Peppermint: This popular oil is used for headaches, pain, and stomach issues like irritable bowel syndrome.
  • Rose: One of the more expensive essential oils, this highly prized soothing floral scent may ease stress and menstrual cramps.
  • Rosemary: Distilled from the cooking herb, rosemary essential oil is believed to enhance mental focus and is being studied for the prevention of dementia.
  • Sandalwood: Popular in meditation centers and spas, this fragrant earthy scent is thought to relieve anxiety and improve sleep.
  • Tea tree: This distinctively-scented oil is used to treat fungal skin infections and as a spot treatment for acne.
  • Ylang ylang: Used to relieve pain, reduce inflammation, improve mood, and enhance libido, research shows this oil also may lower blood pressure.

Possible Side Effects

When used as directed, essential oils have few side effects or risks, although the way a given oil is used has a great deal of bearing on its safety. 

Inhaling the scent of essential oils is the safest way to use them. The potential side effects of breathing in an essential oil are minor and, depending on the oil, include headache, nausea, burning of eyes and throat, cough, or shortness of breath. These side effects typically resolve when the scent is no longer detectable.

Topical application of essential oils is generally safe, however, certain oils can cause a reaction that may include contact dermatitis, burns, and skin irritation. A patch test should always be done when using a new essential oil to see if you're sensitive to it.

Certain oils increase photosensitivity and may increase the risk of sunburn, especially citrus oils, such as lemon, lime, grapefruit, bergamot, and tangerine. It's advisable to stay out of the sun for 24 hours after applying any of these oils to your skin.

Ingesting essential oils is not always safe and depends on the oil. Many essential oils are FDA-approved as ingredients in food and fragrances and are labeled generally regarded as safe (GRAS). However, some oils can be toxic and only ingested under medical supervision. Use caution when ingesting essential oils and do not swallow large amounts.

Do not use essential oils near your eyes, genitals, or mucous membranes. If you get an oil in your eyes or mucous membrane, you can dilute it with a carrier oil.

Like any health supplements, essential oils may interact with prescription medications when taken internally. Check with your doctor or pharmacist before combining any essential oil with medications.

Oils to Avoid in Pregnancy

People who are pregnant should use essential oils with caution. There are some oils they should steer clear of altogether, according to the International Federation of Professional Aromatherapists: 

  • Oregano 
  • Thyme 
  • Clove 
  • Cinnamon 
  • Cumin 
  • Aniseed 
  • Fennel 
  • Anise 
  • Sweet Birch
  • Wintergreen 
  • Sage 
  • Hyssop

Do not use essential oils in a humidifier, CPAP machine, or any other breathing device.

What to Look For

Because essential oils are not regulated by the FDA, they vary in quality from brand to brand, so it's largely up to the consumer to choose them wisely. The most reputable suppliers analyze their products using gas chromatography-mass spectrometry (GC-MS).

Look for oils sold in dark amber or cobalt blue glass bottles labeled with the Latin name of the plant. Never buy essential oil products packaged in plastic bottles, as the oils can dissolve plastic and become contaminated with it. 

When purchasing oil to use in a diffuser, opt for undiluted oils. These are typically sold in bottles that are 15ml (0.5 fl oz) or smaller. For topical application over large areas of skin, such as massages, diluted oils are the best choice.

Essential oils should be stored in a cool, dark place to prevent spoiling or degrading. With proper storage and handling, they have a shelf life of about a year.

Do not make healthcare decisions regarding the use of essential oils without consulting a practitioner knowledgable in their use, such as a certified aromatherapist, licensed naturopathic doctor, or functional medicine provider.

There are no universally recognized standards, certifications, or designations for essential oils. Terms like "100% pure" or "therapeutic grade" are marketing terms.

The price of an essential oil depends on the plant's availability, the amount of plant material required, and the growing, harvesting, and manufacturing conditions needed to produce the oil.

Jasmine oil, for instance, costs more than many other oils due to the millions of blossoms needed to produce one kilogram of jasmine absolute oil.

A Word From Verywell

Essential oils are used every day to treat a variety of physical and emotional ailments. These oils are not approved by the FDA to treat any condition. Some essential oils have been shown to have medicinal properties but should be used with caution. Ingesting essential oils should only be done under the supervision of a healthcare practitioner.

Disclaimer: The information contained on this site is intended for educational purposes only and is not a substitute for advice, diagnosis or treatment by a licensed physician. It is not meant to cover all possible precautions, drug interactions, circumstance or adverse effects. You should seek prompt medical care for any health issues and consult your doctor before using alternative medicine or making a change to your regimen.

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