When answering this question on the possibility of using soap to cure leg cramp I began looking around for double blind studies related to aromatherapy.

This lead me to the following examples:

Randomized trial of aromatherapy. Successful treatment for alopecia areata.

Nineteen (44%) of 43 patients in the active group showed improvement compared with 6 (15%) of 41 patients in the control group (P = .008).

Aromatherapy as a safe and effective treatment for the management of agitation in severe dementia

Sixty percent (21/35) of the active treatment group and 14% (5/36) of the placebo-treated group experienced a 30% reduction of CMAI score, with an overall improvement in agitation (mean reduction in CMAI score) of 35% in patients receiving Melissa balm essential oil and 11% in those treated with placebo (Mann-Whitney U test; Z = 4.1, p < .0001). Quality of life indices also improved significantly more in people receiving essential balm oil (Mann-Whitney U test; percentage of time spent socially withdrawn: Z = 2.6, p = .005; percentage of time engaged in constructive activities: Z = 3.5, p = .001).

Inhalation Aromatherapy During Radiotherapy

Anxiety scores were significantly lower at treatment completion

These all claim to be randomized double-blind placebo controlled studies.

How valid are studies such as these? Do they indicate that aromatherapy does have some efficacy in treating certain conditions?

1 Answer 1


Some nice finds! I was excited to think that my view of aromatherapy might be overturned.

By the time I finished researching, my excitement had worn off.

Randomized trial of aromatherapy. Successful treatment for alopecia areata.

I was a bit surprised by this study, as the treatment was rubbing oils into the affected areas (scalp), which seems to me to be less about the "influence of aroma on the brain, especially the limbic system through the olfactory system" (Wikipedia) and more about topical application of drugs. This seems far less implausible, but apparently it still counts as aromatherapy.

The study was examined in June 2000 in Aromatherapy: a systematic review, Brian Cooke and Edzard Ernst, British Journal of General Practice, 2000, 50, 493-496.

In it, they classified it as one of six "‘one-off’ trials of aromatherapy with no independent replication."

The studies were too heterogeneous and had no common denominator in terms of end-point evaluated for meta-analysis to be attempted. The highest Jadad score achieved in any of these trials was 2 (out of a possible 5).

While the implication about Jadad scores is unfortunate, asking for independent replication so soon after the study came out strikes me as a little unfair. I looked for some later reviews.

I found this:

Aromatherapy with essential oils (thyme, rosemary, lavender, and cedarwood) massaged daily was compared with carrier oil in 86 people with alopecia areata and they were followed up after 3 months and 7 months [Hay et al, 1998]. Independently assessed photographic evidence was collected throughout the trial and any degree of improvement was measured using a six-point scale and computerized analysis of affected areas. Nineteen people in the active treatment group (n = 43) showed improvement, compared with six people in the control group (n = 41), which was a highly significant difference. However, the study had several limitations:

  • It was not clear how long the treatment was given for.
  • Thirteen people dropped out of the control group, reducing the impact of the apparent benefit achieved with aromatherapy.
  • Some people had other types of treatment before the study was discontinued but no more details were provided.
  • It is assumed that the treatment and intervention groups had similar baseline profiles in terms of extent and pattern of alopecia areata but details were not provided.
  • Note: manufacturers of aromatherapy products are not bound by statutory monitoring or good manufacturing requirements and there is no formal recognized standardization of active ingredients in aromatherapy products.

Complementary and alternative medicines: use in skin diseases, Magin, Parker; Adams, Jon, Expert Review of Dermatology, Volume 2, Number 1, February 2007 , pp. 41-49(9)

I looked for a Cochrane Review (see below for what they are) to see if, perhaps, one of the oils used is considered a conventional, topical treatment for alopecia areata. I found that there are no known good treatments:

Treatments for alopecia areata, alopecia totalis and alopecia universalis

There is no good trial evidence that any treatments provide long-term benefit to patients with alopecia areata, alopecia totalis and alopecia universalis. [...] We found 17 randomised controlled trials involving 540 participants. Only one study which compared two topical corticosteroids showed significant short-term benefits. No studies showed long-term beneficial hair growth. None of the included studies asked participants to report their opinion of hair growth or whether their quality of life had improved with the treatment.

Delamere FM, Sladden MJ, Dobbins HM, Leonardi-Bee J, Interventions for alopecia areata, Cochrane Database of Systematic Reviews 2008, Issue 2. Art. No.: CD004413. DOI: 10.1002/14651858.CD004413.pub2

So, this study has been criticised for a number of reasons and dismissed. My conjecture that the oils themselves (and not their aromas) might have some effect is not supported by evidence.

Aromatherapy as a safe and effective treatment for the management of agitation in severe dementia

This is the study that got me excited, because I couldn't see any immediate flaws myself.

It's a small study, so I went to the Cochrane Collaboration to see how it fit in with other studies in the area. Cochrane are a highly respected organisation that do meta-analyses, examining all the published studies in an area to review their methods and to pool their data.

In 2003, (and still up-to-date as of 2008), they published a short review on the topic of aromatherapy and dementia.

The one small trial published is insufficient evidence for the efficacy of aroma therapy for dementia Aroma therapy is the use of pure essential oils from fragrant plants (such as Peppermint, Sweet Marjoram, and Rose) to help relieve health problems and improve the quality of life in general. The healing properties of aroma therapy are claimed to include promotion of relaxation and sleep, relief of pain, and reduction of depressive symptoms. Hence, aroma therapy has been used to reduce disturbed behaviour, to promote sleep and to stimulate motivational behaviour of people with dementia. Of the four randomized controlled trials found only one had useable data. The analysis of this one small trial showed a significant effect in favour of aroma therapy on measures of agitation and neuropsychiatric symptoms. More large-scale randomized controlled trials are needed before firm conclusions can be reached about the effectiveness of aroma therapy.

Holt FE, Birks TPH, Thorgrimsen LM, Spector AE, Wiles A, Orrell M. Aroma therapy for dementia. Cochrane Database of Systematic Reviews 2003, Issue 3. Art. No.: CD003150. DOI: 10.1002/14651858.CD003150

They go on to explain: They looked at four published papers, including Ballard 2002 (i.e. the one you cite), and found none of them could be used as is, but they went and requested the data from the authors of the Ballard study and re-did the statistics, and confirmed it did show a statistically significant treatment effect.

Inhalation Aromatherapy During Radiotherapy

If we quote a little bit more of the abstract we get a very different result:

Results: There were no significant differences in HADS depression or SPHERE scores between the randomly assigned groups. However, HADS anxiety scores were significantly lower at treatment completion in the carrier oil only group compared with either of the fragrant arms (P = .04).

Conclusion: Aromatherapy, as administered in this study, is not beneficial.

Note: This indicates, if anything, that aromatherapy is harmful (causes anxiety), compared to the control.

There appears to have been some unblinding due to the fragrance, so even that result isn't terribly convincing; see Table 1 and also the statement:

None of the patients in the carrier oil–only arm requested dose reductions (achieved by using fewer drops); whereas, 35% of the patients in the fragrant arms requested this because of the initial strength of the olfactory sensation.

  • Thanks for taking the time to do this. Big plus for mentioning the Cochrane Collaboration, something I am interested in finding out more about by myself as it sounds like a valuable asset.
    – going
    Commented Aug 6, 2011 at 8:11
  • It is worth noting, as you say, that aromatherapy is normally through massage with essential oils, and so is the topical application of (possible) drugs. I image with willow-bark you would find pain-killing effects! (Aspirin precursor)
    – Nick
    Commented Aug 30, 2012 at 12:43

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