What Are Essential Oils, and Do They Work?
Written by Helen West, RD on September 30, 2019
Essential oils are often used in aromatherapy, a form of alternative medicine that employs plant extracts to support health and well-being.
However, some of the health claims associated with these oils are controversial.
This article explains all you need to know about essential oils and their health effects.null
What are essential oils?
Essential oils are compounds extracted from plants.
The oils capture the plant’s scent and flavor, or “essence.”
Unique aromatic compounds give each essential oil its characteristic essence.
Essential oils are obtained through distillation (via steam and/or water) or mechanical methods, such as cold pressing.
Once the aromatic chemicals have been extracted, they are combined with a carrier oil to create a product that’s ready for use.
The way the oils are made is important, as essential oils obtained through chemical processes are not considered true essential oils.
Essential oils are concentrated plant extracts that retain the natural smell and flavor, or “essence,” of their source.
How do essential oils work?
Essential oils are most commonly used in the practice of aromatherapy, in which they are inhaled through various methods.
Essential oils are not meant to be swallowed.
The chemicals in essential oils can interact with your body in several ways.
When applied to your skin, some plant chemicals are absorbed (1Trusted Source, 2Trusted Source).
It’s thought that certain application methods can improve absorption, such as applying with heat or to different areas of the body. However, research in this area is lacking (3Trusted Source, 4Trusted Source).
Inhaling the aromas from essential oils can stimulate areas of your limbic system, which is a part of your brain that plays a role in emotions, behaviors, sense of smell, and long-term memory (5Trusted Source).
Interestingly, the limbic system is heavily involved in forming memories. This can partly explain why familiar smells can trigger memories or emotions (6Trusted Source, 7Trusted Source).
The limbic system also plays a role in controlling several unconscious physiological functions, such as breathing, heart rate, and blood pressure. As such, some people claim that essential oils can exert a physical effect on your body.
However, this has yet to be confirmed in studies.
Essential oils can be inhaled or diluted and applied to the skin. They may stimulate your sense of smell or have medicinal effects when absorbed.
There are more than 90 types of essential oils, each with its own unique smell and potential health benefits.
Here’s a list of 10 popular essential oils and the health claims associated with them:
- Peppermint: used to boost energy and aid digestion
- Lavender: used to relieve stress
- Sandalwood: used to calm nerves and help with focus
- Bergamot: used to reduce stress and improve skin conditions like eczema
- Rose: used to improve mood and reduce anxiety
- Chamomile: used to improve mood and relaxation
- Ylang-Ylang: used to treat headaches, nausea, and skin conditions
- Tea Tree: used to fight infections and boost immunity
- Jasmine: used to help with depression, childbirth, and libido
- Lemon: used to aid digestion, mood, headaches, and more
There are over 90 commonly used essential oils, each associated with certain health claims. Popular oils include peppermint, lavender, and sandalwood.
Health benefits of essential oils
Despite their widespread use, little is known about the ability of essential oils to treat certain health conditions.
Here’s a look at the evidence regarding some of the common health problems that essential oils and aromatherapy have been used to treat.
Stress and anxiety
It has been estimated that 43% of people who have stress and anxiety use some form of alternative therapy to help relieve their symptoms (8Trusted Source).
Regarding aromatherapy, initial studies have been quite positive. Many have shown that the smell of some essential oils can work alongside traditional therapy to treat anxiety and stress (9Trusted Source, 10Trusted Source, 11Trusted Source).
However, due to the scents of the compounds, it’s hard to conduct blinded studies and rule out biases. Thus, many reviews on the stress- and anxiety-relieving effects of essential oils have been inconclusive (12Trusted Source, 13Trusted Source).
Interestingly, using essential oils during a massage may help relieve stress, although the effects may only last while the massage is taking place (14Trusted Source).
A recent review of over 201 studies found that only 10 were robust enough to analyze. It also concluded that aromatherapy was ineffective at treating anxiety (15Trusted Source).
Headaches and migraines
In the ’90s, two small studies found that dabbing a peppermint oil and ethanol mixture on participants’ foreheads and temples relieved headache pain (16Trusted Source, 17Trusted Source).
Recent studies have also observed reduced headache pain after applying peppermint and lavender oil to the skin (18Trusted Source, 19Trusted Source).
What’s more, it has been suggested that applying a mixture of chamomile and sesame oil to the temples may treat headaches and migraines. This is a traditional Persian headache remedy (20Trusted Source).
However, more high-quality studies are needed.
Sleep and insomnia
Smelling lavender oil has been shown to improve the sleep quality of women after childbirth, as well as patients with heart disease (21Trusted Source, 22Trusted Source).
One review examined 15 studies on essential oils and sleep. The majority of studies showed that smelling the oils — mostly lavender oil — had positive effects on sleep habits (23Trusted Source).
It has been suggested that essential oils may help fight inflammatory conditions. Some test-tube studies show that they have anti-inflammatoryeffects (24Trusted Source, 25Trusted Source).
One mouse study found that ingesting a combination of thyme and oregano essential oils helped induce the remission of colitis. Two rat studies on caraway and rosemary oils found similar results (26Trusted Source, 27Trusted Source, 28Trusted Source).
However, very few human studies have examined the effects of these oils on inflammatory diseases. Therefore, their effectiveness and safety are unknown (29Trusted Source, 30Trusted Source).
Antibiotic and antimicrobial
The rise of antibiotic-resistant bacteria has renewed interest in the search for other compounds that can fight bacterial infections.
Test-tube studies have investigated essential oils, such as peppermint and tea tree oil, extensively for their antimicrobial effects, observing some positive results (31Trusted Source, 32Trusted Source, 33Trusted Source, 34Trusted Source, 35Trusted Source, 36Trusted Source, 37Trusted Source, 38Trusted Source, 39Trusted Source).
However, while these test-tube study results are interesting, they do not necessarily reflect the effects that these oils have within your body. They don’t prove that a particular essential oil could treat bacterial infections in humans.
Essential oils may have some interesting health applications. However, more research is needed in humans.
Essential oils have many uses outside of aromatherapy.
Many people use them to scent their homes or freshen up things like laundry.
They are also used as a natural scent in homemade cosmetics and high-quality natural products.
What’s more, it has been suggested that essential oils could provide a safe and environmentally friendly alternative to man-made mosquito repellents, such as DEET.
However, results regarding their effectiveness have been mixed.
Studies have shown that some oils, such as citronella, may repel certain types of mosquitoes for around 2 hours. Protection time may be extended up to 3 hours when it’s used in combination with vanillin.
Furthermore, the properties of essential oils indicate that some of them could be used industrially for extending the shelf life of foods (39Trusted Source, 40Trusted Source, 41Trusted Source, 42Trusted Source).
Aromatherapy isn’t the only use for essential oils. They can be used in and around the home, as a natural mosquito repellent, or industrially to make cosmetics.
How to choose the right essential oils
Many companies claim that their oils are “pure” or “medical grade.” However, these terms aren’t universally defined and therefore hold little weight.
Given that they’re products of an unregulated industry, the quality and composition of essential oils can vary greatly (43Trusted Source).
Keep the following tips in mind to choose only high-quality oils:
- Purity: Find an oil that contains only aromatic plant compounds, without additives or synthetic oils. Pure oils usually list the plant’s botanical name (such as Lavandula officinalis) rather than terms like “essential oil of lavender.”
- Quality: True essential oils are the ones that have been changed the least by the extraction process. Choose a chemical-free essential oil that has been extracted through distillation or mechanical cold pressing.
- Reputation: Purchase a brand with a reputation for producing high-quality products.
High-quality oils only use pure plant compounds extracted by distillation or cold pressing. Avoid oils that have been diluted with synthetic fragrances, chemicals, or oils.
Safety and side effects
Just because something is natural doesn’t mean it’s safe.
Plants and herbal products contain many bioactive compounds that may harm your health, and essential oils are no different.
However, when inhaled or combined with a base oil for use on your skin, most essential oils are considered safe. Be sure to consider others in your environment who might be inhaling the aroma, including pregnant women, children, and pets.
Nevertheless, they may cause some side effects, including (44Trusted Source):
- asthma attacks
- allergic reactions
While the most common side effect is a rash, essential oils can cause more serious reactions, and they have been associated with one case of death (45Trusted Source).
The oils that have most commonly been associated with adverse reactions are lavender, peppermint, tea tree, and ylang-ylang.
Oils that are high in phenols, such as cinnamon, can cause skin irritation and shouldn’t be used on the skin without being combined with a base oil. Meanwhile, essential oils made from citrus fruits increase the skin’s reaction to sunlight and burns can occur.
Swallowing essential oils is not recommended, as doing so could be harmful and, in some doses, fatal (46Trusted Source, 47Trusted Source).
Very few studies have examined the safety of these oils for pregnant or breastfeeding women, who are usually advised to avoid them (48Trusted Source, 49Trusted Source, 50Trusted Source, 51Trusted Source, 52Trusted Source).
Essential oils are generally considered safe. However, they may cause serious side effects for some people, especially if applied directly to the skin or ingested.
The bottom line
Essential oils are generally considered safe to inhale or apply to the skin if they’ve been combined with a base oil. They should not be eaten.
However, evidence supporting many of their associated health claims is lacking, and their effectiveness is often exaggerated.
For minor health problems, using essential oils as a complementary therapy is likely harmless.
However, if you have a serious health condition or are taking medication, you should discuss their use with your healthcare practitioner.
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