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Clinical Assistant Professor, Department of Family Medicine, University of Wisconsin; Clinical Assistant Professor of Medicine, Arizona Center for Integrative Medicine, University of Arizona, Tucson
Dr. Kiefer reports no financial relationships relevant to this field of study.
SYNOPSIS: After four weeks, people with allergic rhinitis in both an herbal steam bath group and a control group showed improvements in some typical rhinitis symptoms.
SOURCE: Tungsukruthai P, Nootim P, Worakunphanich W, Tabtong N. Efficacy and safety of herbal steam bath in allergic rhinitis: A randomized controlled trial. J Integr Med 2018;16:39-44.
The spring allergy season is upon us, and patients will be looking for effective treatments to address sinus congestion and pain, rhinorrhea, sneezing, and itchy eyes. There are a host of over-the-counter and prescription pharmaceutical options available, but people often turn to dietary supplements, including herbal medicines, for symptomatic relief. One such treatment genre is herbal steams or inhalations, often using essential oils in hot water, which then volatilize, are inhaled, and have a variety of purported effects on the upper respiratory tract. But do they work? Tungsukruthai et al attempted to explore such herbal inhalants through a study on traditional herbal steam baths in Thailand.
The study took place in Bangkok and involved adults with allergic rhinitis as diagnosed by a healthcare provider. Of the 130 research participants selected, 62 were excluded because of pregnancy, lactation, recent nasal surgery, fever, dizziness, insomnia, starvation [sic], dermatitis, open skin lesions, or allergies to heat, herbal medicines, or steam. The 68 remaining participants were randomized to an herbal steam bath group (n = 34) and a steam bath group without the herbal medicines added to the steam (n = 34). The steam treatments occurred for 30 minutes three times weekly for four weeks. Assessments took place as per Table 1. The visual analog scale (VAS) for allergic rhinitis symptoms ranged from 0 for no bothersome symptoms to 10 for extremely bothersome symptoms. The quality of life scale contained seven items, each of which was a five-point rating. There were also questions (rated on a three-point scale) pertaining to satisfaction with the treatment, including the steam bath in general, cabinet conditions, the steam bath process, treatment duration, and then related to nose symptoms, sleep quality, and ability of the steam to reduce symptoms.
The herbal medicines used in the steam bath are listed in Table 2, including their Latin binomial scientific name, common name (English), and plant part used, if listed. These plants were steeped in water 108-113° F, and steam from this water (or plain water for the control group) was infused into a small “cabinet” made from pine wood, with a seat, door, and vents, in which the study participants would sit.
Of the 68 people enrolled in the study, 64 completed the protocol. Two participants in each group dropped out: three moved out of the area and one failed to attend the follow-up sessions. Baseline demographics were similar between the two groups. Overall, the two groups did not differ statistically in terms of allergic rhinitis symptoms after four weeks, although there were some improvements (slightly different in each group) over baseline. (See Table 3.) The data were represented as a mean ± a standard deviation. Most numbers were in the range of 0.8 to 1.5 based on gross VAS numbers of 10 to 25, just to give some context for the clinical applicability of the results seen.
With respect to quality of life, there was no difference between the two groups at the end of the intervention. In contrast, the herbal steam bath group reported higher satisfaction with the treatment than the control group (2.75 mean ± standard deviation in the herbal group at week 4 vs. 1.64 in the control group; P < 0.05).
The researchers also commented on safety, mentioning that there were no “serious adverse effects,” although the details about this were not provided. Specifically, the authors only wrote that one study participant in the control group had 10 minutes of itching.
There are several interesting layers to this study, not the least of which is the cultural context of steam baths and the specific plants in Thai traditional medicine. The authors mentioned that the plants used were
“fragrant” and “generally liked” by Thai people, which could account for the greater satisfaction with the steam treatment in the herbal group compared to the control group. Also, saunas and steam baths are a part of Thai traditional healing and are used for a variety of medical conditions. However, the results seem to indicate that the steam itself may be the primary driver of allergic rhinitis symptomatic improvement.
There are two criticisms of the study. First, the plant formulations are incomplete; it would be useful to know what plant part(s) were used for the cinnamon (likely the bark) and camphor (likely drops). This would allow for the protocol and treatments to be replicated most effectively or incorporated into a clinical practice. Also, there is likely no way to conduct a double-blind trial given the fragrance of the herbal steam baths; the results could have been swayed by the participants’ knowledge of which group they were assigned.
A challenge exists trying to extrapolate these results to clinical situations in the United States, not uncommon as integrative providers attempt to benefit from effective treatments from other regions and cultures. So can we translate these results to the myriad of essential oil treatments available in the United States? Herbal “inhalants” are used commonly to treat sinus congestion, allergies, and upper respiratory tract infections, but the plants
used in this study differed from those typically used as antivirals and mucolytics in Western herbal medicine. A variety of essential oils, from peppermint (Mentha x piperita) to sage (Salvia officinalis) to eucalyptus (Eucalyptus globulus), can be administered via steam, which, upon contact to mucus membranes of the upper respiratory tract, can lead to thinning of the mucus, enhanced ciliary action, and mucus clearance, all contributory mechanisms to people suffering from allergic rhinitis or other sinus conditions.1 It is unclear if the plants in this study have locally acting effects beyond the familiarity and likeability of the aromas, not to be minimized but physiologically a gap in potential benefit for patients. Perhaps the lack of a local effect for the plants tested explains why the herbal and control groups had similar allergic rhinitis outcomes at the end of the four weeks. Another physiological comment is that any of these plants, the Thai and Western herbs alike, are missing an antihistamine effect; as we all know, histamine is one of the common causative biochemical agents underlying the seasonal or year-round rhinorrhea and itchy eyes. However, for a short-term, locally acting effect, herbal steams with Western herbs, possibly Thai herbs, may play a role, and the steam itself seems to be beneficial.
The “recommendation” above is not to say that herbal inhalants are free from adverse effects. Some essential oils, when inhaled, can be dangerous in small children; eucalyptus may lead to glottal spasm and respiratory arrest.2 Any inhalant could exacerbate asthma. Because of concerns about hepatotoxicity and other untoward effects, no essential oil should be ingested orally unless under the guidance of an herbal expert, and even then only for some plants in very small amounts. The authors added to the cautions list by excluding pregnant women from the study, commenting on safety concerns with saunas and steam baths in that demographic.
Putting this all together, this was a good attempt to study a traditional treatment in a quantitative way. There is some indication that steam, and possibly steam with traditional Thai herbs, has some benefits on allergic rhinitis symptoms and patient satisfaction. The challenge will be to arrange for this type of treatment (30 minutes three times weekly for four weeks in a steam “cabinet”) in a typical clinic in the United States. Barring a few cautions, if our patients have access to a sauna or steam bath, we can encourage them to use that resource to help them through symptomatic times of their allergies.
Financial Disclosure: Integrative Medicine Alert’s Executive Editor David Kiefer, MD; Peer Reviewer Suhani Bora, MD; Relias Media Executive Editor Leslie Coplin; Editor Jonathan Springston; Editorial Group Manager Terrey L. Hatcher; and Accreditations Manager Amy M. Johnson, MSN, RN, CPN, report no financial relationships relevant to this field of study.