Wintergreen essential oil Reviews

Botanical Nomenclature: Gaultheria procumbens
Extraction Method: Distillation

Wintergreen essential oil, which is distilled from the leaves of Gaultheria procumbens, is widely used in the flavoring and toiletries industries. Today, wintergreen is used to flavor a variety of liquors and is among the most popular of all flavors for oral care products like mouthwash and toothpaste.

The manufacturing process used to make wintergreen oil produces methyl salicylate and it’s this compound that is responsible for wintergreen’s ability to ease pain and reduce minor inflammation.

Today, wintergreen is among the most controversial of all the essential oils. Wintergreen poisonings have been reported around the world and wintergreen is actually listed as a known toxin by the regulatory agencies of many countries. Some aromatherapists have even called for a worldwide ban on the sale of this once extremely popular oil.

Characteristics of Wintergreen Oil

Wintergreen essential oil should be pale yellow to pale reddish-yellow. Wintergreen has a sharp, “minty” scent that should be familiar to anyone who has ever used a wintergreen-flavored mouthwash or toothpaste. Wintergreen will feel cold to the nose and somewhat “wet”.

Psychological Aromatherapy

Because of its potential toxicity, wintergreen essential oil is rarely used these days in casual aromatherapy. Author Salvatore Battaglia lists it among his “hazardous” essential oils and does not recommend its use.

Traditional Uses for Wintergreen Oil

Various wintergreen preparations have been used throughout the centuries to reduce swelling and reduce pain. But aromatherapy expert Salvatore Battaglia feels that the potential toxicity of wintergreen outweighs its potential benefits and does not assign any therapeutic actions to it.

Serious Medical Studies on Wintergreen

Considering that wintergreen is so widely used in over-the-counter pain topical pain relievers, it is surprising that few recent studies have been published on the essential oil. In preparation for this article, we were only able to locate studies discussing wintergreen’s potential toxicity and could find no recent studies on any medicinal benefits.

Safety Issues

Wintergreen oil is 98% methyl salicylate and any volume greater than a lick or a taste is enough to poison an infant or preschooler. Just 4 ml, which is less than half a typical bottle of essential oil, is enough to fatally poison a school-aged child.

And wintergreen does not have to be ingested to be toxic. Transdermal absorption is also a very effective delivery method for the salicylate component. In fact, a 2002 paper printed in the journal Emergency Medicine discussed the case of a young man who was poisoned after using a naturopath-prescribed wintergreen cream for his psoriasis.

It’s little wonder that some in the aromatherapy community have called for a complete cessation of the use of wintergreen oil in aromatherapy and a ban on the sale of the oil to unlicensed practitioners.


Battaglia, S. (2005). The Complete Guide to Aromatherapy.

Chyka, P., et al. (2007). Salicylate poisoning: an evidence-based consensus guideline for out-of-hospital management.

Bell, A., et al. (2002). Acute methyl salicylate toxicity complicating herbal skin treatment for psoriasis.

Camphor essential oil Reviews

Botanical Nomenclature: Cinnamomum camphora
Extraction Method: Distillation

Camphor essential oil is usually just referred to as “camphor oil” with the “essential” left off. Perhaps this is because camphor oil is made by a multi-step process that involves processing the wood of a Japanese native called Cinnamomum camphora. The Japanese know it as Hon-Sho.

To make camphor oil, all useable wood, including the stumps and small branches, are gathered then distilled. This produces a crude oil and a crystalline substance called crude camphor. The crude camphor is then pressed and filtered to extract what is called crude camphor oil. The crude camphor oil is then further rectified then pressed and filtered until 3 separate “grades” of camphor oil are achieved.

The lightest of these is called white camphor and is the one most often used in “natural” medicine. Second are medium-to-heavy fractions known as brown or yellow camphor. Last in line is blue camphor—a heavy fraction rich in sesquiterpenes.

Characteristics of Camphor Oil

Camphor oil should be colorless or very pale yellow. It has a biting, overwhelming scent that is strongly medicinal and somewhat “minty”. It will feel very cold and wet to the nose.

Traditional Uses for Camphor

Over the years, various camphor preparations—crude and refined—have been considered highly anti-microbial and were often used to aid breathing during a cold or other respiratory illness. Camphor essential oil has also seen extensive use as a topical pain reliever. It is a popular ingredient in over-the-counter muscle liniments, topical arthritis remedies and “vapor rubs”.

Serious Medical Studies on Camphor

Insect Repellence

A number of aromatherapy oils have been studied over the years for their potential to ward of pests like ticks and mosquitoes. In addition to repelling many of the insects that damage food crops, camphor oil has shown great promise in the fight against the mosquito that carries yellow fever.

Anti-Candida Actions

Camphor has long been considered anti-microbial and recent studies supports this. A 2007 study from India found camphor among the essential oils demonstrating anti-microbial action against one of the most common human infections, Candida.

Safety Issues

If ingested, camphor can cause vomiting, apnea, seizures and even death. A 2007 paper published in Cardiovascular Toxicology discussed the case of a patient who nearly died from inflammation of the heart muscle after consuming camphor oil.

How common is camphor poisoning? In the years between 1990 and 2003, the poison centers in the U.S. logged more than 10,000 cases of camphor essential oil poisoning each year.

Camphor does not have to be ingested to be dangerous. A 2007 article in Emergency Medicine Journal discussed the case of a young boy who experienced epileptic seizures after his nanny rubbed a “natural” flatulence remedy onto his abdomen.


Battaglia, S. (2005). The Complete Guide to Aromatherapy.

Yang, Y., et al. (2004). Repellency of aromatic medicinal plant extracts and a steam distillate to Aedes aegypti.

Dutta, B., et al. (2007). Anticandidial activity of some essential oils of a mega biodiversity hotspot in India.

Bhaya, M., et al. (2007). Camphor induced myocarditis: a case report.

AAPCC. (2006). Camphor Poisoning: an evidence-based practice guideline for out-of-hospital management.

Guilbert, J., et al. (2007). Anti-flatulence treatment and status epilepticus: a case of camphor intoxication.

Boldo Essential Oil Review

Botanical Nomenclature: Peumus boldus
Extraction Method: Distillation 

Boldo essential oil is distilled from the leaves of Peumus boldus, a small tree that grows wild in parts of South America. Indigenous people in the Andes Mountains have used boldo medicinally for years.

Characteristics of Boldo Oil

Boldo oil is yellow in color and, like most other distilled oils, thin. It has a strong spicy scent. George Burdock, of Fenaroli’s Handbook of Flavor Ingredients, describes the scent has “similar to melissa”.

Psychological Aromatherapy

Though various preparations of boldo have been used or centuries, today’s aromatherapists agree that essential oil of boldo should not be used in aromatherapy, due to its ascaridole content.

Traditional Uses for Boldo Oil

Though there’s little evidence that an essential oil of boldo was ever used medicinally, various cultures in its native South America used other boldo preprations (especially infusions) for infections, arthritis and even liver and gall bladder disorders.

Perhaps boldo was best-known as a treatment for gonorrhoea. It was extensively used for inflammation of the genitals and urinary tract.

Serious Medical Studies on Boldo Oil

In preparation for this article, we could find no scientific studies on the use of boldo oil for any medical condition.

Safety Issues

Boldo is not considered safe for aromatherapy—at least by most popular aromatherapy authors—mainly due to its ascaridole content. Like most other essential oils, boldo hasn’t been exhaustively studied.


Battaglia, S. (2005). The Complete Guide to Aromatherapy.

Burdock, G. (2004). Fenaroli’s Handbook of Flavor Ingredients.

Vogel, H. (1999). Studies of Genetic Variation of Essential Oil and Alkaloid Content in Boldo (Peumus boldus).

Atlas Cedarwood Essential Oil Health Benefits

Botanical Nomenclature: Cedrus atlantica
Extraction Method: Distillation 

Atlas cedarwood essential oil, which is also known as Moroccan cedarwood or just atlas cedar, was once used in embalming, as an antiseptic for wounds and, according to the Bible, was even the type of cedar used to build Solomon’s temple. No wonder its very name comes to us from an ancient Arabic word that translates into “power”.

Today’s atlas cedarwood essential oil is distilled from the mature wood of the Cedrus atlantica. Some popular aromatherapy texts have vilified this oil, confusing it with oil made from C. libani, a rare and protected species.

According to aromatherapy aficionados, the best atlas cedarwood oil is made from the heartwood of trees that are between 20 and 30 years old. Today, most of this oil is actually produced from sawdust or wood chips left over from the furniture or lumber industries.

Characteristics of Atlas Cedar

Atlas cedarwood oil can range in color from deep yellow to amber. It should be noticeably more viscous than other distilled oils and will have a somewhat unpleasant top note of camphor. Underneath is a warm, woody scent that can seem somewhat sweet in the nose.

Psychological Aromatherapy

Psychological aromatherapists call atlas cedarwood “tonic”, “grounding” and “strengthening”. It is often used to convey a sense of confidence and integrity to a space. At least one popular aromatherapy writer refers to the atlas personality as confident and secure.

Traditional Uses for Atlas Cedar Oil

Atlas cedarwood was traditionally used mainly for its believed anti-microbial properties. The ancient Egyptians documented their use of cedarwood in the embalming process and as recently as the 20th century, atlas cedarwood was studied for its ability to address conditions like bronchitis.

Aromatherapist Salvatore Battaglia assigns atlas cedarwood essential oil these therapeutic properties:

  • Antiseptic
  • Antiseborrheic
  • Astringent
  • Diuretic
  • Expectorant
  • Insecticidal
  • Sedative

Serious Studies on Atlas Cedar Oil

A 2003 Japanese study looking at 12 popular essential oils listed atlas cedarwood among the essential oils that successfully inhibited the invasion of Candida albicans into mucus membranes. This could sometime make atlas cedarwood an effective part of a natural approach to oral and vaginal yeast infections.

This study seems to support the findings of another 2003 study—this one from Korea—which looked at various essential oils and their actions against Aspergillus niger, and Aspergillus flavus. Unfortunately, in this study, cedarwood showed less promise as an antifungal remedy.

Safety Issues

Like many essential oils, atlas cedarwood has not been exhaustively studied for long-term use or safety. Aromatherapists are somewhat divided on this issue with some calling cedarwod non-toxic and non-sensitizing. Others label it “contra-indicated” for pregnancy. Unfortunately, there simply isn’t enough scientific evidence to support either position at this time.


Battaglia, S. (2005). The Complete Guide to Aromatherapy.

Abe, S., et al. (2003). Anti-Candida albicans activity of essential oils including Lemongrass (Cymbopogon citratus) oil and its component, citral.

Shin, S. (2003). Anti-Aspergillus activities of plant essential oils and their combination effects with ketoconazole or amphotericin B.

Clove essential oil Review

Botanical Nomenclature: Syzygium aromaticum
Extraction Method: Distillation/Rectification

Clove essential oil is made by distilling either the leaves or flower buds of Szygium aromaticum, which is a tree grown mainly for the spice market. Most of the major healing modalities—Ayurveda, TCM and Western herbalism—use clove preparations for various medicinal purposes.

Legend tells us that at various times throughout history, European healers used clove buds to freshen the air and protect against the most common pathogens of the day.

Characteristics of Clove Oil

Clove oil can range from pale yellow to brown, depending upon which part of the plant was used. All clove oils should have an overpowering “spicy” bite them with strong “woody” notes. Some clove oils are somewhat sweet-smelling while others can feel quite dry to the nose.

Psychological Aromatherapy

In Chinese medicine all preparations of clove are thought to stimulate Qi so it will come as no surprise that nearly all of today’s aromatherapy authors also associate clove essential oil with warming, energizing qualities. 

Traditional Uses for Clove

Today, clove is used mainly as a spice but in centuries past various clove preparations were an important herbal medicine. Traditional Chinese medicine uses clove to aid digestion while modern European herbalism uses clove preparations to cleanse the mouth and support oral health. In fact, one of clove essential oil’s best-known uses is for dental health. Most of the popular aromatherapy books mention clove oil as a home remedy for toothache.

Salvatore Battaglia lists the following therapeutic actions in his clove oil monograph:

  • Analgesic
  • Antiseptic
  • Antisposmodic
  • Carminative & Stomachic


Serious Medical Studies on Clove Essential Oil

Clove has long been associated with the prevention of infections. Today many of the recent studies on clove essential oil have focused on agricultural and commercial uses but a few medicinal studies stand out:

Antifungal Actions

Clove’s eugenol content, which can approach 90%, is thought to be responsible for clove’s ability to fight various fungal infections. A 2007 Korean study published in the Journal of Microbiology found clove oil diluted to 0.2 mg/ml effective at a rate of 60% when tested against some of the most common dermatophytes.

A similar study, this one looking at clove’s effectiveness against Candida, found clove essential oil a “powerful” and “easily accessible” remedy against strains that cause most human yeast infections.

Antiviral Actions

In laboratory tests, clove oil demonstrates the ability to effectively arrest the replication of various Herpes strains. Again, it seems to be the eugenol content that is responsible for this action.

Dust Mites

One of the most interesting recent studies on clove oil looked at clove’s ability to fight one of the most common household allergens—dust mites. Exactly how (or even if) this discovery will ever be put into practical use remains to be seen but clove was among several oils shown to kill this common pest.

Safety Issues

Clove is a strong dermal irritant and may well be one of the best-documented irritants of all the common aromatherapy oils. Numerous reports of both allergy and sensitization have been published throughout the years and, today, many aromatherapy books recommend that clove essential oil never be used on the skin, even if properly diluted.

Clove is also a potential poison and it takes surprisingly little to cause serious health problems. In 1991 a 7-month-old child was nearly killed after he accidentally ingested clove essential oil. This report mirrors the experience of a slightly older toddler who experienced liver failure in 2005 after ingesting only 10 ml of the oil.


Battaglia, S. (2005). The Complete Guide to Aromatherapy.
Lalko, J., et al. (2005). Investigation of the dermal sensitization potential of various essential oils in the local lymph node assay.
Lane, B., et al. (1991). Clove oil ingestion in an infant.
Janes, S., et al. (2005). Essential oil poisoning: N-acetylcysteine for eugenol-induced hepatic failure and analysis of a national database.
Park, M., et al. (2007). Antifungal activities of the essential oils in Syzygium aromaticum (L.) Merr. Et Perry and Leptospermum petersonii Bailey and their constituents against various dermatophytes.
Chaieb, K., et al. (2007). Antioxidant properties of the essential oil of Eugenia caryophyllata and its antifungal activity against a large number of clinical Candida species.
Tragoolpua, Y., et al. (2007). Anti-herpes simplex virus activities of Eugenia caryophyllus (Spreng.) Bullock & S. G. Harrison and essential oil, eugenol.
Saad, et al. (2006). Acaricidal activities of some essential oils and their monoterpenoidal constituents against house dust mite, Dermatophagoides pteronyssinus (Acari: Pyroglyphidae).

Fennel essential oil Review

Botanical Nomenclature: Foeniculum vulgare
Extraction Method: Distillation

Fennel essential oil is somewhat unique because while most essential oils are made by distilling flowers, leaves or bark, fennel is different. It’s made by crushing and then distilling the seeds of F. vulgare.

This perennial herb, which may be biennial in some areas, has two subspecies and the essential oil produced from each is very different from the other. The variety known as amara gives us bitter fennel while the variety known as dulce gives us the more familiar sweet fennel.

Characteristics of Fennel Oil

Fennel essential oil should be a pale yellowish color with a sweet “soil” scent that has undertones of pepper and spice. It should feel a bit dry in the nose.

Psychological Aromatherapy

Aromatherapist Patricia Davis calls fennel an effective defense against evil forces and recommends it whenever you feel threatened by a “psychic attack”. Other aromatherapists use fennel to help open creative channels and reduce overly-analytical thinking.

Traditional Uses for Fennel Oil

Various preparations made from fennel have been used throughout history to help purge congestion, ease menstrual issues and promote the flow of urine. But perhaps fennel’s best-known use is as a stomach ailment. Fennel was actually approved by Germany’s Commission E, which is similar to our FDA, for peptic ulcers, spastic colon and flatulence.

Aromatherapy author Salvatore Battaglia assigns the following actions to fennel essential oil:

  • Antiseptic
  • Antispasmodic
  • Carminative
  • Depurative
  • Diuretic
  • Emmenagogue
  • Expectorant
  • Splenic
  • Stomachic

Scientific Studies on Fennel Oil

Anti-Microbial Activities In Soil

In controlled tests, fennel essential oil showed what researchers called “marked antifungal activity” against one of the most damaging plant pathogens, Sclerotinia sclerotiorum. When tested on soil used to grow tomatoes, fennel essential oil increased the survival rate of seedlings by more than 50%.

Diuretic Properties

Fennel has been a long-time favorite diuretic among herbalists and a 2007 study published in the Journal of Enthopharmacology listed fennel as first among a number of essential oils studied for diuretic actions.


Tuberculosis kills 3 million people around the world every year and drug-resistant strains are becoming more and more common. But in the future, perhaps essential oils like fennel may be used to fight this aggressive and often deadly disease.

A 2007 study published in the journal Phytotherapy Research found fennel essential oil among the oils that showed at least some activity against dug-resistant strains of tuberculosis. In fact, although fennel had to be used at a higher “dose” than the best-performing oil, it was one of only two oils that showed activity against all TB strains tested in this study.

Tumors & Cancer

While fennel often doesn’t perform as well as other botanical extracts against tumors, a few studies suggest that fennel may have some potential as an anti-cancer agent. One of the most recent studies finding in favor of fennel was a 2007 report in the the Journal of Ethnopharmacology.


In Germany, fennel essential oil is an approved remedy for peptic ulcers. A study in the journal World Journal of Gastroenterology is only the latest in a line of studies proving that fennel can reduce, and even prevent, some types of damage to the intestinal tract.

Fennel has also been studied for other digestive complaints, including constipation, IBS and similar conditions. Fennel is one of the ingredients in the popular herbal tea Smooth Move.

Safety Issues

As is the case with all botanical extracts, most of the research is done in vitro or on animals. Like other essential oils, fennel has not been exhaustively studied for long-term or high-dose use in humans.

Many popular aromatherapy texts contraindicate fennel for those with epilepsy and those who are pregnant and nursing. Some caution against any oral uses at all. While scientific support for these positions is scant, we do know that fennel contains potentially troublesome chemical components like trans-anethole, which is suspected of having hormone-influencing qualities.


Battaglia, S. (2005). The Complete Guide to Aromatherapy

Soylu, S., et al. (2007). Antifungal effects of essential oils from oregano and fennel on Sclerotinia sclerotiorum.

Wright, C., et al. (2007). Herbal medicines as diuretics: A review of the scientific evidence.

Camacho-Corona, M., et al. (2007). Activity against drug resistant-tuberculosis strains of plants used in Mexican traditional medicine to treat tuberculosis and other respiratory diseases.

Kaileh, M., et al. (2007). Screening of indigenous Palestinian medicinal plants for potential anti-inflammatory and cytotoxic activity.

Birdane, F., et al. (2007). Beneficial effects of Foeniculum vulgare on ethanol-induced acute gastric mucosal injury in rats.

Bub, S., et al. (2006). Efficacy of an herbal dietary supplement (Smooth Move) in the management of constipation in nursing home residents: A randomized, double-blind, placebo-controlled study.

Bilia, A., et al. (2000). Identification by HPLC-DAD and HPLC-MS analyses and quantification of constituents of fennel teas and decoctions.

Carrot Seed Essential Oil Review

Botanical Nomenclature: Daucus carota
Extraction Method: Distillation

Carrot seed essential oil is made not from edible kitchen-variety carrots but from a European species known as “wild” carrots and has grown in popularity recently as a additive in various skin care products. It’s rarely used as a diffused oil, though. Most commonly, carrot seed oil is prized for its vitamin A component and is added to soaps, body creams and even natural sunscreens.

Carrot seed oil is distilled from the seeds of Daucus carota. There is a carrot root oil made through chemical extraction of the roots (the part we normally just refer to as “carrots”) but this oil is extremely rare and normally not available to those outside the cosmeseutical industry.

Characteristics of Carrot Seed Oil

Carrot seed oil should be pale yellow to amber in color with an “organic”, earthy scent reminiscent of fresh garden soil. There should be a slightly sweet top note that gives way to a vaguely spicy undertone. Carrot seed oil may feel full and dry to the nose.

Psychological Aromatherapy

To our knowledge, carrot seed oil isn’t used in psychological aromatherapy. But Salvatore Battaglia quotes another aromatherapy author when he says that carrot seed oil personalities are associated with “egoism” and “sense of self”.

Traditional Uses for Carrot Seed Oil

Its high vitamin A content makes carrot seed essential oil a popular additive in “natural” cosmetics, especially skin care creams targeting the “mature skin” market. In his book The Complete Guide to Aromatherapy, Salvatore Battaglia also assigns the following actions to carrot seed essential oil:

  • Carminative
  • Cytophylactic
  • Depurative
  • Emmenagogue
  • Diurteic
  • Hepatic

Scientific Studies on Carrot Seed Oil

Given its relatively anonymity in American aromatherapy, it may be surprising to learn that carrot seed essential oil has seen its share of scientific studies.

Campylobacter Fighter

Campylobacter is a genus of bacteria responsible for sickening over 1 million Americans every year. This makes Campylobacter one of the most common diarrhea-causing illnesses in the U.S. And immune-compromised people who contract this disease can actually die from the infection.

But a 2007 study published in the Journal of Agricultural Food Chemistry found that carrot seed essential oil showed great promise against several strains of Campylobacter, including one multi-drug resistant strain of C. jejuni.

Helicobacter pylori

The discovery of the link between ulcers and a strain of bacteria called Helicobacter pylori revolutionized the way this very common stomach condition is treated. A 2003 animal study of various essential oils and their actions against H. pylori produced somewhat disappointing results but in more than 20% of the animals given carrot seed oil orally, the infection cleared. Researchers aren’t sure why carrot seed oil performed so well compared to other oils but this research is certainly intriguing.

Antifungal Actions

In addition to its proven antibacterial activity, carrot seed oil also shows great potential as an antifungal agent. A 2004 study published in a Polish journal found that one of the main constituents of carrot seed oil, carotol, inhibited fungal growth by as much as 65% in laboratory tests.

Safety Issues

Like most essential oils, carrot seed hasn’t been tested for safety or toxicity. Today’s aromatherapy books list carrot seed oil as non-toxic, non-irritating and non-sensitizing. In preparation for this article, we could find no documented cases of carrot oil toxicity or sensitization.


Battaglia, S. (2005). The Complete Guide to Aromatherapy

CDC. (2005). Campylobacter Infections.

Jasicka-Misiak, I., et al. (2004). Antifungal activity of the carrot seed oil and its major sesquiterpene compounds.

Rossi, P., et al. (2007). (E)-Methylisoeugenol and elemicin: antibacterial components of Daucus carota L. essential oil against Campylobacter jejuni.

Bergonzelli, G., et al. (2003). Essential oils as components of a diet-based approach to management of Helicobacter infection.

Yarrow essential oil Review

Botanical Nomenclature: Achillea millefolium
Extraction Method: Distillation 

Yarrow essential oil is distilled from the leaves and flowering tops of Achillea millefolium, a prennenial creeper that now grows wild throughout much of the world. Its species name, mmillefolium pays homage to its feathered leaves and, according to legend, the name of its genus, Achillea, comes from the mythical soldier Achilles, who, according to the legend, made a wound-healing remedy from the plant and used the ointment to treat battle wounds.

Characteristics of Yarrow Oil

Depending on its azulene content, yarrow essential oil can range from olive-green to dark blue. Yarrow has a strong camphorous scent that mellows into a less-harsh, sweeter scent.

Psychological Aromatherapy

In causal aromatherapy yarrow is used to reopen the flow of Qi and release pent-up emotions. Popular aromatherapists write that yarrow is a good oil to diffuse for people who struggle with unresolved anger, bitterness and disappointment.

Traditional Uses for Yarrow

Over the centuries, various yarrow preparations have been used to stimulate menstruation, address a variety of vaginal irritations and restore hormonal harmony. Yarrow infusions are also considered astringent and antiseptic and are often recommended for a variety of skin conditions, especially inflammatory conditions like acne.

Salvatore Battaglia assigns the following therapeutic actions to yarrow essential oil:

  • Anti-inflammatory
  • Astringent
  • Anti-spasmodic
  • Carminative & Digestive
  • Diophoretic
  • Emmenagogue
  • Expectorant
  • Stomachic
  • Tonic

Serious Medical Studies on Yarrow Oil

A surprising number of scientific studies have been done on yarrow essential oil and its potential health benefits.

Digestive Support

Yarrow has long been considered an appetite stimulator and a 2007 animal study from Scotland seems to support this use. This study looked at the effect of 5 herbs on the digestive systems of young chickens. Young chicks given supplements of yarrow herb and essential oil gained weight more easily and increased their body mass, compared to chicken who ate diets supplemented with other herbs.

Antioxidant Activity

A number of studies have found various species of yarrow to be rich in antioxidants. One of the most recent was a 2003 study published in Journal of Ethnopharmacology which looked specifically at A. millefolium.

Antimicrobial Effects

Yarrow oil is rich in germ-killing compounds like camphor and eucalyptol. In laboratory tests, yarrow oil demonstrates antimicrobial activities against the germs that are responsible for pneumonia, vaginal yeast infections and even the most common cause of food poisoning.

Safety Issues

Most popular aromatherapy texts list yarrow as non-toxic and non-irritating but the sesquiterpenes, which can vary from growing area to growing area may explain why some users experience allergic skin reactions when using yarrow oil in aromatherapy.

Yarrow oil is sometimes listed in popular aromatherapy texts as an emmenagogue. Like most other essential oils, yarrow hasn’t been exhaustively tested for safety during pregnancy and lactation although a 2004 animal study published in Reproductive Toxicology found no link between yarrow exposure and reproductive issues in young rats.

This study seems to support the findings of a 2003 study from Australia which studied the effect of yarrow on pregnant rats. Even at 56 times the human dose, yarrow was not linked to miscarriage or uterine contractions. However, birth weights of the resulting newborns was reduced, leading researchers in this study to contraindicate yarrow for use during pregnancy until further study could be done.


Battaglia, S. (2005). The Complete Guide to Aromatherapy.

Cross, D., et al. (2007). The effect of herbs and their associated essential oils on performance, dietary digestibility and gut microflora in chickens from 7 to 28 days of age.

Orav, A., et al. (2006). Phytochemical analysis of the essential oil of Achillea millefolium L. from various European Countries.

Dalsenter, P., et al. (2004). Reproductive evaluation of aqueous crude extract of Achillea millefolium L. (Asteraceae) in Wistar rats.

Boswell-Ruys, C., et al. (2003). Preliminary screening study of reproductive outcomes after exposure to yarrow in the pregnant rat.

Candan, F. (2003). Antioxidant and antimicrobial activity of the essential oil and methanol extracts of Achillea millefolium subsp. millefolium Afan. (Asteraceae).

Grapefruit essential oil Review

Botanical Nomenclature: Citrus paradisiC. racemosa
Extraction Method: Cold pressing

Grapefruit essential oil is made from the only variety of citrus that’s native to the Americas. It’s thought that today’s grapefruit trees are the result of a cross between other citrus species brought to the West Indies by Spanish explorers in the 1600s.

Regardless of grapefruit’s exact origins, there’s no doubt that this large and sometimes bitter fruit is immensely important to a number of industries. While it’s only recently been “discovered” by aromatherapy, grapefruit has long been used to flavor foods and scent toiletries like soaps, shampoos and lotions.

Like all other citrus fruits, grapefruit essential oil is expeller pressed from the rinds of its ripe fruit. Both “white” grapefruit and “red” or “ruby” grapefruit can be used to make essential oil. The only significant difference is a slightly higher aldehyde in the “white” varieties.

In shopping for grapefruit oil, you may find a number of species represented as “grapefruit”. Perhaps the most common oil is C. paradisi. It’s believed to be a hybrid of C. maxima and C. sinensis.

Characteristics of Grapefruit Oil

Grapefruit essential oil is a thin, yellow or yellow-green oil with a definite “citrus” scent. It should be less sweet than sweet orange but less harsh than bergamot. It will feel a bit “wet” to the nose and a tad drier than orange.

Psychological Aromatherapy

Like other citrus oils, grapefruit appeals to people who are warm, happy and generally optimistic. Grapefruit may feel a bit more sophisticated than other citrus oils and is a good oil for people who feel stressed or tense.

Grapefruit can be a fantastic substitute for heavier, sweeter citrus oils. Lisa Barger calls it “the grown-up’s citrus”.

Traditional Uses for Grapefruit Oil

Generally, grapefruit oil is considered more similar to lemon than other citrus oils. Author Salvatore Battaglia assigns the following therapeutic actions to grapefruit:

  • Antidepressant
  • Antiseptic
  • Depurative
  • Diuretic
  • Disinfectant
  • Stimulant

Scientific Studies on Grapefruit Oil

Weight Loss

As surprising as it seems, grapefruit essential oil, diffused into the air, may help some people lose weight. A 2005 Japanese study on rats found that exposure to the scent of grapefruit essential oil directly affected the adrenal glands and, in the words of researchers, “inhibited the parasympathetic gastric nerve”.

This study found that a 15-minute exposure to the scent of grapefruit essential oil 3 times a week effectively reduced food intake—apparently by directly suppressing the appetite. To date, no human studies have been published but the results seem very promising.


The various citrus oils have long been associated with detoxification and a 2003 suggests that the limonene content of citrus oils may also have strong anti-cancer properties. This study found that limonene and other chemical components of citrus oils induced apoptosis, or cell death, when put into direct contact with tumor cells. How this may someday benefit human cancer patients has yet to be determined.

Antibiotic Resistant Bacteria

As drug-resistant “super bugs” become more and more common, science is increasingly looking to botanical medicine for help. A 2004 study from the UK suggests that adding grapefruit essential oil to the standard antibiotic methicillin increases the effectiveness of the drug even on strains of Staph that are resistant to the drug.

Safety Issues

Grapefruit is know to interact with or influence the metabolism of a number of medications. To date, all studies on grapefruit’s potential drug interactions has focused on ingested grapefruit and not on the potential effects of inhaling the vapor of the essential oils. How, or even if, the casual use of grapefruit essential oil in aromatherapy could cause drug interactions is unknown at this time.

In popular aromatherapy texts, grapefruit oil is considered non-toxic and non-sensitizing. And unlike other citrus oils, grapefruit shows very little potential for phototoxicity.


Battaglia, S. (2005). The Complete Guide to Aromatherapy

Stump, A., et al. (2006). Management of Grapefruit-Drug Interactions.

Shen, J., et al. (2005). Olfactory stimulation with scent of grapefruit oil affects autonomic nerves, lipolysis and appetite in rats.

Hata, T., et al. (2003). Induction of apoptosis by Citrus paradisi essential oil in human leukemic (HL-60) cells.

Abulrob, A., et al. (2004). Identification and biological evaluation of grapefruit oil components as potential novel efflux pump modulators in methicillin-resistant Staphylococcus aureus bacterial strains.

Black pepper essential oil Review

Botanical Nomenclature: Piper nigrum
Extraction Method: Distillation 

Black pepper essential oil may not sound like a promising new tool in the aromatherapist’s arsenal but this unfamiliar essence may well be one of the most promising essential oils around.

Native to Indonesia and southern India, the plant that gives us black pepper has been cultivated by humans for more than 2,000 years. This perennial flowering vine produces small fruits that, when allowed to ripen, produce the spice we call white pepper. But if those fruits are picked before they’re allowed to fully mature, the resulting pepper is known as black pepper. And it’s from those unripe fruits, with their berries still intact, that essential oil producers distill their precious essential oil.

Characteristics of Black Pepper Oil

Depending upon the ripeness of the fruits used to make it, black pepper oil will range from colorless to pale green. All black pepper should have a warm, spicy wood scent with a definite “pepper” smell.

Psychological Aromatherapy

Aromatherapy regards black pepper oil as “warming” and “tonifying”. It is often diffused to dispel melancholy and to strengthen reserve. Spiritual aromatherapists tell us that people who feel especially drawn to black pepper are responsible but often self-righteous people with strong leadership skills and a “can-do” attitude.

Traditional Uses for Black Pepper Oil

Traditionally, pepper has been used mainly to stimulate organs like the spleen. Author Salvatore Battaglia assigns the following actions to the essential oil:

  • Analgesic
  • Antiseptic
  • Antispasmodic
  • Carminative
  • Diaphoretic
  • Diuretic
  • Laxative
  • Tonic
  • Stomachic

Scientific Studies on Black Pepper Essential Oil

As is the case with other culinary spices, much of the research on black pepper has focused on the ground spice and not on the essential oil. While laboratory tests have shown that black pepper may have anti-inflammatory, anti-microbial and antioxidant activities, only one peer-reviewed human study on the oil itself was found in the course of our investigation of this oil.

Effect on the Sympathetic Nervous System

Your sympathetic nervous system, or SNS, is the branch of your autonomic nervous system responsible for the fight-or-flight response during times of stress. A 2002 Japanese study found that inhalation of black pepper oil caused a 1.7 fold increase in hormones associated with the fight-or-flight response. Exactly how this information will prove useful has yet to be determined.

Safety Issues

Like many essential oils, black pepper has not been exhaustively studied for side effects. Most aromatherapy texts list black pepper oil as non-irritating and non-sensitizing but, again, this has not been proven scientifically.


Battaglia, S. (2005). The Complete Guide to Aromatherapy.

Haze, S., et al. (2002). Effects of fragrance inhalation on sympathetic activity in normal adults.