About the Research Databases

The Wellness Evidence team of doctor consultants selected four of the most respected evidence-based medicine databases that are also particularly useful for wellness-focused research: Natural Standard, The Cochrane Library, PubMed and the TRIP Database.

Please read “Important Things to Know,” including info on each database.

We’ve made researching a particular therapy simple by pre-searching the evidence at each database. (See evidence below.) However, please note that evidence-based medicine relies on a research hierarchy, because not all evidence is created equalLearn more about how the medical experts classify this research.

We’d like to hear from you. If there is a Wellness Evidence discipline you would like to see on these pages, please email us.

Natural Standard

An international research collaboration that systematically reviews (and limits its focus to) scientific evidence on complementary and alternative medicine (CAM). Founded in 2000, Natural Standard assigns a grade to each CAM therapy, reflecting the level of available scientific data for or against the use of each therapy for a specific medical condition.

Natural Standard is subscription-based, and each of the database’s monographs aggregates data from other resources like AMED, CANCERLIT, CINAHL, CISCOM, the Cochrane Library, EMBASE, HerbMed, International Pharmaceutical Abstracts, Medline and NAPRALERT – and 20 additional journals. Data analysis is performed by healthcare professionals conducting clinical work and/or research at academic centers, using standardized instruments pertaining to each monograph section


Fragrant oils have been used for thousands of years to lubricate the skin, purify air, and repel insects. Ancient Egyptians used fragrant oils for bathing and massage. Essential oils of plants have been used medicinally through application directly to the skin (usually diluted), as a part of massage, added to bathwater, via steam inhalation, or in mouthwashes.

Aromatherapy is a technique in which essential oils from plants are used with the intention of preventing or treating illness, reducing stress, or enhancing well-being. Fragrance oils and products containing man-made compounds are not used in the practice of genuine aromatherapy. Although many gift shops sell scented candles, pomanders, and potpourri as “aromatherapy,” genuine aromatherapy treatments use higher strength (concentrated) essential oils drawn from various herbs.

There is no formal training or licensing procedure for aromatherapists in the United States. This technique is offered by a wide range of practitioners with licenses in other fields, including massage therapists, chiropractors, and other therapists.

Evidence Table
The grades A-F ascribed to the specific health conditions below have a very specific meaning. i.e., a “C” can still mean evidence of benefit from a small randomized trial, etc. Read about what each grade actually means. Grade
Agitation in patients with dementia
Aromatherapy using essential oil of lemon balm (Melissa officinalis) may reduce agitation in people with severe dementia, when applied to the face and arms. Other research reports that steam inhalation of lavender aromatherapy may have similar effects. Overall, the evidence does suggest potential benefits.
Alcohol withdrawal
Aromatherapy may be as effective as some types of acupuncture in treating alcohol withdrawal symptoms. More study is needed in this area.
Alopecia areata (hair loss)
Alopecia areata is a disorder in which the body’s immune system attacks hair follicles, resulting in unpredictable patches of hair loss. Early evidence suggests a blend of essential oils rubbed into the scalp may show benefit.
Anxiety (lavender aromatherapy)
Lavender aromatherapy may be able to reduce anxiety. However, there have been conflicting results, and more study is needed in this area.
Anxiety (sandalwood aromatherapy in palliative care)
Lavender may contribute to reduced anxiety and improved mood, at least subjectively, but some other aromas, such as sandalwood, may not. More studies are needed to confirm these findings.
Anxiety/stress in intensive care unit patients (lavender aromatherapy)
It is unclear whether lavender aromatherapy reduces anxiety levels in intensive unit care patients.
Arthritis (wellbeing)
There is not enough scientific evidence to recommend for or against the use of aromatherapy in arthritis patients.
Atopic eczema (children)
It is unclear whether aromatherapy might benefit children with atopic eczema.
Cancer (quality of life)
Aromatherapy is often used in people with chronic illnesses (frequently in combination with massage), with the intention to improve quality of life or well- being. There is not enough scientific evidence in this area.
Aromatherapy may be helpful during childbirth to relieve anxiety, pain, nausea, and/or vomiting or to strengthen contractions. It may also reduce pain perceived by first time mothers.
Chronic obstructive pulmonary disease (COPD)
Early evidence suggests that aromatherapy may aid mucus clearance in COPD. More studies are needed before conclusions about this application of aromatherapy can be made.
Early research in Guillian Barr? syndrome patients show a possible benefit of aromatherapy massage for constipation, and rosemary, lemon, and peppermint essential oils may be beneficial in the elderly. Additional study is warranted to differentiate the effects of essential oils vs. massage.
Decongestant-expectorant/upper respiratory tract infection (eucalyptus aromatherapy)
Despite widespread use in over-the-counter agents and vapors, there is not enough scientific evidence to recommend use of eucalyptus oil as a decongestant-expectorant (by mouth or inhaled form).
There is not enough scientific evidence to recommend for or against the use of aromatherapy in patients with mild depression.
Abdominal aromatherapy massage with a combination of essential oils may reduce the intensity of menstrual cramps in women with dysmenorrhea. More research is needed in this area to identify the most effective essential oils.
Itching (pruritus) in dialysis patients
Preliminary research reports reduced itching in dialysis patients receiving aromatherapy massage. Further research is necessary before a firm conclusion can be drawn.
Massage and skin care with and without aromatherapy improved relief and wellbeing in breast cancer patients. More study is needed in this area.
Nausea and vomiting (post-operative)
There is not enough scientific evidence to recommend for or against the use of aromatherapy in patients with post-surgery nausea.
It has been suggested that aromatherapy massage may reduce abdominal obesity or appetite. Additional evidence is needed before a clear conclusion can be reached.
Perineal discomfort after childbirth
Early research on the use of essential oils in bath water or soap suggests limited or no benefit for post-partum perineal discomfort. More studies are needed before conclusions can be reached about this application of essential oils.
Postpartum care
Aromatherapy is popularly used to improve mood. A preliminary study found that aromatherapy in first-time mothers had improved moods after aromatherapy. Higher quality research is needed in this area.
Sleep apnea (pediatric)
Early research suggests that pre-mature newborns with sleep apnea may benefit from aromatherapy. However, more data are needed before definitive recommendations can be made.
Sleep quality (adults)
Early research suggests that lavender may have general benefits for sleep quality and specific benefits for insomnia.
Stroke recovery
There is not enough scientific evidence to recommend for or against the use of aromatherapy in recovering stroke patients.
Wound care
Early research suggests that aromatherapy may contribute to reduced pain intensity during dressing changes in wound care. More study is needed in this area.

A variety of mechanisms have been proposed for the reported effects of aromatherapy. It has been suggested that following placement of oil onto the skin, or breathing in fragrant air, the odor-sensing nerves in the nose are stimulated, sending impulses to the limbic system of the brain (a center for processing of emotions). A different theory is that some oils directly interact with hormones or enzymes in the blood, or stimulate the adrenal glands. Scientific research is limited in these areas, and it remains unclear how specific types of aromatherapy may work in the body.

There are more than 100 essential oils commonly used for aromatherapy. These oils are extracted from flowers (rose, narcissus), roots (orris), leaves and needles (eucalyptus, pine), resins (turpentine), seeds (caraway), fruits (lemon, lime), berries (cloves), bark (cinnamon) and wood (cedar). Many are obtained from familiar herbs and spices (basil, anise, nutmeg, cumin, oregano), and many are derived from substances related to herbal medicine (ginger, garlic, St. John’s wort).


The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

Acne, addiction, allergies, Alzheimer’s disease, antibacterial, anticonvulsant, antifungal, antiviral, asthma, autonomic dysfunction, back pain, bereavement/grief, bladder infections, boils, bronchitis, burns, chronic bronchitis (prevention and treatment), chronic pain, circulation, cognitive performance enhancement, common cold, confidence boosting, coping skills, digestion disorders, exercise recovery, exhaustion, fever, gas, Guillian-Barre syndrome (symptom relief), headache, high blood pressure, hormonal disorders, immune system stimulant, impatience, impotence, improving circulation, indigestion, infections (intravenous/Hickman line), inflammation, insect bites, irregular heartbeat, irritability, joint pain, labor pain, laryngitis, liver disorders, loss of appetite, maternal comfort during labor, memory enhancement, menstrual cramps, motion sickness, mucositis, muscle pain, nausea, nerve pain, pain, palliative care, panic attacks, pimples, prevention of respiratory tract infections, psoriasis, psychosomatic illness, reducing swelling after injuries, relieving menstrual symptoms, restlessness, rheumatic disorders, seizure disorder, sexually transmitted diseases, skin infections, skin rash in bone marrow transplant patients (engraftment syndrome rash), smoking withdrawal symptoms, spasms, sprains and strains, stimulation of digestion, stomach complaints, sunburn, study performance (math tasks), swelling, tendonitis, vaginitis, yeast infections.


Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.

Skin rash (dermatitis) from direct contact with various essential oils has been reported in humans, and skin irritation can develop with regular use. Peppermint and eucalyptus oils may burn the skin if applied at full strength. With the possible exception of lavender, essential oils should be diluted with a base oil before use to avoid skin irritation. Severe phototoxicity/photosensitivity (skin sensitivity to light) may occur, particularly with oil of bergamot. Vapors from aromatherapy may irritate the eyes, and patients are advised to keep their eyes closed while inhaling aromatic vapors.

Allergy may occur with use of essential oils, and may be due to contamination, or to constituents of the herb(s) from which the oil is derived. In cases of suspected skin allergy, some aromatherapists will place a single drop of oil on the skin to see if a reaction occurs over 24 hours. Individuals who have difficulty breathing with the use of aromatherapy should seek medical attention before attempting aromatherapy again.

Oils applied to the skin or inhaled through the nose and mouth can be absorbed into the body and can have systemic effects. There are reports of agitation, drowsiness, nausea, and headache with the use of aromatherapy. Some oils are thought to have toxic effects on the brain, liver and kidney, or to increase the risk of cancer with long-term use. Aromatherapies that may increase sedation or drowsiness, such as lavender or chamomile, may add to the effects of drugs, herbs, or supplements that also cause fatigue or sedation. Caution is advised in people who are driving or operating heavy machinery.

Essential oils may be toxic if taken by mouth, and should not be swallowed. Fragrances may contain unknown and potentially toxic contaminants. There are reports that lead emission may occur from the burning wick of aromatherapy candles, although long-term health effects are not clear.

Based on human use, sage, rosemary, and juniper oils may cause the uterus to contract when taken in large amounts. Due to these reports, and lack of reliable safety data, the use of these oils is discouraged during pregnancy.

Infants and young children may be especially sensitive to the effects and side effects of essential oils. Peppermint oil is not recommended in children under the age of 30 months. It is suggested to consult a qualified healthcare professional before using aromatherapy in children.


This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com): William Collinge, PhD, MPH (Collinge & Associates); Nicole Giese, MS (Natural Standard Research Collaboration); Michael Goble, BS, PharmD (Massachusetts College of Pharmacy); David Lee, PharmD (Massachusetts College of Pharmacy-Worcester); John Markowitz, PharmD (Medical University of South Carolina); Catherine Ulbricht, PharmD (Massachusetts General Hospital); Wendy Weissner, BA (Natural Standard Research Collaboration); Jen Woods, BS (Natural Standard Research Collaboration).


Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. Selected references are listed below.

  1. Anderson C, Lis-Balchin M, Kirk-Smith M. Evaluation of massage with essential oils on childhood atopic eczema. Phytother Res 2000 Sep;14(6):452-6.
  2. Ballard CG, O’Brien JT, Reichelt K, et al. Aromatherapy as a safe and effective treatment for the management of agitation in severe dementia: the results of a double-blind, placebo- controlled trial with Melissa. J Clin Psychiatry 2002;63(7):553-558.
  3. Barclay J, Vestey J, Lambert A, et al. Reducing the symptoms of lymphoedema: is there a role for aromatherapy? Eur J Oncol Nurs 2006 Apr;10(2):140-9.
  4. Brownfield A. Aromatherapy in arthritis: a study. Nurs Stand 1998 Oct 21-27;13(5):34-5.
  5. Burns E, Zobbi V, Panzeri D, Oskrochi R, et al. Aromatherapy in childbirth: a pilot randomised controlled trial. BJOG 2007 Jul;114(7):838-44.
  6. Cooke B, Ernst E. Aromatherapy: a systematic review. Br J Gen Pract 2000;50(455):493-496.
  7. Gravett P. Aromatherapy treatment for patients with Hickman line infection following high-dose chemotherapy. Internat J Aromather 2001;11(1):18-19.
  8. Han SH, Hur MH, Buckle J, et al. Effect of aromatherapy on symptoms of dysmenorrhea in college students: A randomized placebo-controlled clinical trial. J Altern Complement Med 2006 Jul-Aug;12(6):535-41.
  9. Hay IC, Jamieson M, Ormerod AD. Randomized trial of aromatherapy. Successful treatment for alopecia areata. Arch Dermatol 1998 Nov;134(11):1349-52.
  10. Holmes C, Hopkins V, Hensford C, et al. Lavender oil as a treatment for agitated behaviour in severe dementia: a placebo controlled study. Int J Geriatr Psychiatry 2002 Apr;17(4):305-8.
  11. Muzzarelli L, Force M, Sebold M. Aromatherapy and reducing preprocedural anxiety: A controlled prospective study. Gastroenterol Nurs 2006 Nov-Dec;29(6):466-71.
  12. Smallwood J, Brown R, Coulter F, et al. Aromatherapy and behaviour disturbances in dementia: a randomized controlled trial. Int J Geriatr Psychiatry 2001;16(10):1010-1013.
  13. Smith CA, Collins CT, Cyna AM, Crowther CA. Complementary and alternative therapies for pain management in labour. Cochrane Database Syst Rev 2006 Oct 18(4):CD003521.
  14. Wilkinson S, Aldridge J, Salmon I, et al. An evaluation of aromatherapy massage in palliative care. Palliat Med 1999 Sep;13(5):409-17.
  15. Wilkinson SM, Love SB, Westcombe AM, et al. Effectiveness of aromatherapy massage in the management of anxiety and depression in patients with cancer: a multicenter randomized controlled trial. J Clin Oncol 2007 Feb 10;25(5):532-9.


British epidemiologist Archie Cochrane is regarded as the originator of the Evidence-Based Medicine concept (in the 1950s). And the Cochrane Library is a collection of very high-quality medical databases, which have, at their core, the Cochrane Reviews, systematic reviews and meta-analyses which summarize and interpret the results of well-conducted, randomized controlled trials… the ‘gold standard’ in Evidence-Based Medicine.

The Cochrane Library is a subscription-based database but offers free access to abstracts.


The TRIP Database, launched in 1997, is a search engine designed to allow clinicians to quickly find answers to their medical questions using the best available evidence. Trip’s founders realized medical professionals were being forced to perform time-consuming searches at multiple websites to get at the most relevant information. So, they designed TRIP as a meta-search engine, allowing users to both simultaneously search thousands of databases, medical publications and resources, as well as easily filter the results: limiting searches to the most stringent, highest-quality medical evidence or expanding them to include results like patient information, news articles, etc.


The TRIP Database, launched in 1997, is a search engine designed to allow clinicians to quickly find answers to their medical questions using the best available evidence. Trip’s founders realized medical professionals were being forced to perform time-consuming searches at multiple websites to get at the most relevant information. So, they designed TRIP as a meta-search engine, allowing users to both simultaneously search thousands of databases, medical publications and resources, as well as easily filter the results: limiting searches to the most stringent, highest-quality medical evidence or expanding them to include results like patient information, news articles, etc.