Summaries of Some Studies of Some Essential Oils

There have been several studies of the antibacterial, antimicrobial, antiseptic, antiviral, antifungal, antioxidant, insecticide/repellant and other properties of some EOs. There have been some studies on the effects on blood pressure, wound healing, glucose tolerance levels, stress, depression, cognition, and mood using several EOs, and studies on the effectiveness of topical (massage, soap, sitz bath or compress), burning candle, and aromatherapy (aroma vapor inhalation) application methods. Also, some EOs were identified as sensitizers to a subset of people already sensitive to fragrances. Study results are very promising, although more testing needs to be done. The organic growth and production of Mother Nature's remedies does not pollute the air, water, or earth. They're at least as effective, sometimes more effective, than those noxious synthetic chemicals we've been sold.

Remember, NEVER APPLY UNDILUTED ESSENTIAL OILS TO THE SKIN. NEVER INGEST ESSENTIAL OILS. Below are are few selected summaries. All will open in a separate window or tab (see more using the search box at the top of the linked page):

Inhibition by the essential oils of peppermint and spearmint of the growth of pathogenic bacteria.
The effects of the essential oils of peppermint (Mentha piperita L.), spearmint Mentha spicata L.) and Japanese mint (Mentha, arvensis L.), of four major constituents of the esssential oil of peppermint, and of three major constituents of the essential oil of spearmint, on the proliferation of Helicobacter pylori, Salmonella enteritidis, Escherichia coli O157:H7, methicillin-resistant Staphylococcus aureus (MRSA) and methicillin sensitive Staphylococccus aureus (MSSA) were examined. The essential oils and the various constituents inhibited the proliferation of each strain in liquid culture in a dose-dependent manner. In addition, they exhibited bactericidal activity in phosphate-buffered saline. The antibacterial activities varied among the bacterial species tested but were almost the same against antibiotic-resistant and antibiotic-sensitive strains of Helicobacter pylori and S. aureus.
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The effect of aroma inhalation method on stress responses of nursing students
RESULT: As a result of administering aroma inhalation to nursing students, their physical symptoms decreased, their anxiety scores were low, and their perceived stress scores were low, showing that aroma inhalation could be a very effective stress management method.
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The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris
CONCLUSION: Topical 5% tea tree oil is an effective treatment for mild to moderate acne vulgaris.
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Anticandidial activity of some essential oils
Six essential oils viz. Eucalyptus citriodora, Cymbopogon citratus, Callistemon lanceolatus, Cinnamomum camphora, Citrus limon, Tagetes petula, as well as two standard antibiotics, miconazole and clotrimazole, were tested in vitro for their anticandidial activity. All these essential oils exhibited higher activity than the two synthetic antibiotics.
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Treatment of dandruff with 5% tea tree oil shampoo.
CONCLUSION: Five percent tea tree oil appears to effective and well tolerated in the treatment of dandruff.
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Randomized trial of aromatherapy. Successful treatment for alopecia areata.
CONCLUSIONS: The results show aromatherapy to be a safe and effective treatment for alopecia areata. Treatment with these essential oils was significantly more effective than treatment with the carrier oil alone
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A comparative study of tea-tree oil versus benzoylperoxide in the treatment of acne
The results of this study showed that both 5% tea-tree oil and 5% benzoyl peroxide had a significant effect in ameliorating the patients' acne by reducing the number of inflamed and non-inflamed lesions (open and closed comedones), although the onset of action in the case of tea-tree oil was slower. Encouragingly, fewer side effects were experienced by patients treated with tea-tree oil.
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An evaluation of aromatherapy massage in palliative care.
Massage with or without essential oils appears to reduce levels of anxiety. The addition of an essential oil seems to enhance the effect of massage and to improve physical and psychological symptoms, as well as overall quality of life.
See: link. Related study states: "CONCLUSION: Aromatherapy massage does not appear to confer benefit on cancer patients' anxiety and/or depression in the long-term, but is associated with clinically important benefit [for] up to 2 weeks after the intervention."

Essential oils of spices and herbs (thyme, origanum, mint, cinnamon, salvia and clove)
were found to possess the strongest antimicrobial properties among many tested.
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Clinical trial of aromatherapy on postpartum mother's perineal healing
The methods of aromatherapy were applied sitz bath or soap application using essential oils... CONCLUSION: These findings indicate that postpartum aromatherapy for perineal care could be effective in healing the perineum.
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Aloe vera in dermatology: a brief review.
Topical application of aloe vera...can be effective for genital herpes, psoriasis, human papiloma virus, seborrheic dermatitis, aphthous stomatitis, xerosis, lichen planus, frostbite, burn, wound healing and inflammation. It can also be used as a biological vehicle and an anti-microbial and antifungal agent...
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Frankincense: systematic review.
The included trials related to asthma, rheumatoid arthritis, Crohn's disease, osteoarthritis, and collagenous colitis. Results of all trials indicated that B serrata extracts were clinically effective. Three studies were of good methodological quality. No serious safety issues were noted.
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Screening of plant extracts for antimicrobial activity against bacteria and yeasts with dermatological relevance.
Rosmarinus-, Salvia-, Boswellia- and Harpagophytum-extracts proved to be effective against a panel of bacteria. It is concluded that due to their antimicrobial effects some of the plant extracts may be used for the topical treatment of skin disorders like acne vulgaris and seborrhoic eczema.
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Effects of aroma hand massage on pain, state anxiety and depression in hospice patients with terminal cancer
RESULTS: The aroma hand massage experimental group showed more significant differences in the changes of pain score (t=-3.52, p=.001) and depression (t=-8.99, p=.000) than the control group. CONCLUSION: Aroma hand massage had a positive effect on pain and depression in hospice patients with terminal cancer.
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Inhibitory effect of essential oils against herpes simplex virus type 2.
These results indicate that essential oils affected HSV-2 mainly before adsorption probably by interacting with the viral envelope. Camomile oil exhibited a high selectivity index and seems to be a promising candidate for topical therapeutic application as virucidal agents for treatment of herpes genitalis.
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Vapour-phase activities of essential oils against antibiotic sensitive and resistant bacteria including MRSA.
(Lemongrass & geranium individually & blended called "BioScent" in this study.) CONCLUSIONS: EO vapours inhibited growth of antibiotic-sensitive and -resistant bacteria in vitro and reduced surface and airborne levels of bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Results suggest that EO vapours, particularly Bioscent, could be used as a method of air disinfection.
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The effect of essential oils on methicillin-resistant Staphylococcus aureus using a dressing model.
A combination of Citricidal and geranium oil showed the greatest-anti-bacterial effects against MRSA, whilst a combination of geranium and tea tree oil was most active against the methicillin-sensitive S. aureus (Oxford strain). This study demonstrates the potential of essential oils and essential oil vapours as antibacterial agents and for use in the treatment of MRSA infection.
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Comparative repellency of 38 essential oils against mosquito bites.
When the tested oils were applied at a 10% or 50% concentration, none of them prevented mosquito bites for as long as 2 h, but the undiluted oils of Cymbopogon nardus (citronella), Pogostemon cablin (patchuli), Syzygium aromaticum (clove) and Zanthoxylum limonella (Thai name: makaen) were the most effective and provided 2 h of complete repellency.
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Citrus hystrix vs. cockroach
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Repellency effect of forty-one essential oils against Aedes, Anopheles, and Culex mosquitoes.
The five most effective oils were those of Litsea (Litsea cubeba), Cajeput (Melaleuca leucadendron), Niaouli (Melaleuca quinquenervia), Violet (Viola odorata), and Catnip (Nepeta cataria), which induced a protection time of 8 h at the maximum and a 100% repellency against all three species. This effect needs, however, a peculiar formulation to fix them on the human skin.
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An investigation and comparison of the bioactivity of selected essential oils on human lice and house dust mites.
The most effective essential oil against both lice and mites was tea tree oil; lavender was the second most effective, and lemon oil the least, although it did show activity against mites, unlike lice.
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In vitro antibacterial activity of some plant essential oils.
Cinnamon, clove, geranium, lemon, lime, orange and rosemary oils exhibited significant inhibitory effect. Cinnamon oil showed promising inhibitory activity even at low concentration, whereas aniseed, eucalyptus and camphor oils were least active against the tested bacteria. In general, B. subtilis was the most susceptible. On the other hand, K. pneumoniae exhibited low degree of sensitivity. CONCLUSION: Majority of the oils showed antibacterial activity against the tested strains. However Cinnamon, clove and lime oils were found to be inhibiting both gram-positive and gram-negative bacteria. Cinnamon oil can be a good source of antibacterial agents.
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Interaction of air ions and bactericidal vapours to control micro-organisms.
This study demonstrates the antibacterial properties of ionization products from a candle flame, and that this effect can be significantly increased by the addition of specific-antibacterial compounds, such as orange oil and beta-pinene. The role of both the ionization products from the candle flame and the concentration of volatile compounds released are important to the effect.
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Bactericidal activities of plant essential oils and some of their isolated constituents against Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, and Salmonella enterica.
Campylobacter jejuni - most active against C. jejuni (with BA50 values ranging from 0.003 to 0.009) were marigold, ginger root, jasmine, patchouli, gardenia, cedarwood, carrot seed, celery seed, mugwort, spikenard, and orange bitter oils Escherichia coli O157:H7- active against E. coli (with BA50 values ranging from 0.046 to 0.14) were oregano, thyme, cinnamon, palmarosa, bay leaf, clove bud, lemon grass, and allspice oils Listeria monocytogenes - most active against L monocytogenes (with BA50 values ranging from 0.057 to 0.092) were gardenia, cedarwood, bay leaf, clove bud, oregano, cinnamon, allspice, thyme, and patchouli oils Salmonella enterica - most active against S. enterica (with BA50 values ranging from 0.045 to 0.14) were thyme, oregano, cinnamon, clove bud, allspice, bay leaf, palmarosa, and marjoram oils.
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Antibacterial and antifungal activity of ten essential oils in vitro.
Lemongrass, eucalyptus, peppermint and orange oils were effective against all the 22 bacterial strains. Aegle and palmarosa oils inhibited 21 bacteria; patchouli and ageratum oils inhibited 20 bacteria and citronella and geranium oils were inhibitory to 15 and 12 bacterial strains, respectively. All twelve fungi were inhibited by seven oils (aegle, citronella, geranium, lemongrass, orange, palmarosa and patchouli). Eucalyptus and peppermint oils were effective against eleven fungi.
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The effects of the inhalation method using essential oils on blood pressure and stress responses of clients with essential hypertension.
CONCLUSION: The results suggest that the inhalation method using essential oils can be considered an effective nursing intervention that reduces psychological stress responses and serum cortisol levels, as well as the blood pressure of clients with essential hypertension.
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Antimicrobial and antioxidant activities of Melissa officinalis L. (Lamiaceae) essential oil.
The most effective antibacterial activity was expressed on a multiresistant strain of Shigella sonei. A significant rate of antifungal activity was exhibited on Trichophyton species.
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Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults.
These findings indicate that the olfactory properties of these essential oils can produce objective effects on cognitive performance, as well as subjective effects on mood.
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Effect of aromatherapy on symptoms of dysmenorrhea in college students
CONCLUSIONS: These findings suggest that aromatherapy using topically applied lavender, clary sage, and rose is effective in decreasing the severity of menstrual cramps. Aromatherapy can be offered as part of the nursing care to women experiencing menstrual cramps or dysmenorrhea.
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Fleas/Flies/Ear mites in animals
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Further important sensitizers in patients sensitive to fragrances.
The 6 materials with the highest reactivity after the F[ragrance] M[ix] were ylang-ylang oil (YY) I (2.6%), YY II (2.5%), lemongrass oil (1.6%), narcissus absolute (1.3%), jasmine absolute (1.2%) and sandalwood oil (0.9%).
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