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.

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. Summary 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 ( 1 , 2 ). 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 ( 3 , 4 ). 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 ( 5 ). Interestingly, the limbic system is heavily involved in forming memories. This can partly explain why familiar smells can trigger memories or emotions ( 6 , 7 ). 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. Summary 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.

Popular types 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

used to boost energy and aid digestion Lavender: used to relieve stress

used to relieve stress Sandalwood: used to calm nerves and help with focus

used to calm nerves and help with focus Bergamot: used to reduce stress and improve skin conditions like eczema

used to reduce stress and improve skin conditions like eczema Rose: used to improve mood and reduce anxiety

used to improve mood and reduce anxiety Chamomile: used to improve mood and relaxation

used to improve mood and relaxation Ylang-Ylang: used to treat headaches, nausea, and skin conditions

used to treat headaches, nausea, and skin conditions Tea Tree: used to fight infections and boost immunity

used to fight infections and boost immunity Jasmine: used to help with depression, childbirth, and libido

used to help with depression, childbirth, and libido Lemon: used to aid digestion, mood, headaches, and more Summary There are over 90 commonly used essential oils, each associated with certain health claims. Popular oils include peppermint, lavender, and sandalwood.

Other uses 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 ( 39 , 40 , 41 , 42 ). Summary 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 ( 43 ). 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.”

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.

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. Summary 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 ( 44 ): rashes

asthma attacks

headaches

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 ( 45 ). 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 ( 46 , 47 ). Very few studies have examined the safety of these oils for pregnant or breastfeeding women, who are usually advised to avoid them ( 48 , 49 , 50 , 51 , 52 ). Summary 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.