Washes are prepared by decocting herbs, then applying the liquid as a swab, compress, or bath. They provide soothing relief for itch and pain, reduction of exudation.

The earliest record of eczema was that of “milk ringworm,” which most resembled infantile dermatitis. This dated back to the Sui Dynasty (c. 581–618 A.D).

Later during the Qing dynasty (c. 1644–1911), the “four bends wind” concept was presented. As the name suggested, eczematous skin lesions occurred in the flexural aspects of the arms and legs. Extreme itching and recurrent episodes with copious oozing were included in the description. Subsequently, other dermatitis subtypes such as seborrheic dermatitis, scrotal eczema, and hand eczema were described in significant detail.

The Chinese term for eczema translates directly to “damp rash.” This is derived from the exudation seen in acute eczema. TCM attributes this to internal imbalances, leading to excess dampness and heat. According to TCM, atopic dermatitis (AD) is caused by a congenitally “weak” constitution, which predisposes the individual to extrinsic aggravators such as dietary, lifestyle, and climatic changes. As eczema becomes recurrent and chronic, excessive dampness is said to consume the blood and body fluids (immunological dysfunction), generating dryness, dyspigmentation, and lichenification. At the organ level, AD is also related to dysfunction of the spleen and stomach.

Therefore, while western diagnosis is skin limited, TCM diagnosis strives to clarify the disease syndrome complex underlying it, according to the principles of TCM discussed above.

To date, AD remains a frustrating disease for both patients and doctors alike. As the pathophysiology of AD has not been fully established and there is no apparent cure, treatment has been largely symptomatic. Therapy has, thus far, focused on relief of flares with topical corticosteroids and calcineurin inhibitors, as well as skin barrier therapy with emollients. More severe disease would necessitate oral corticosteroids and immunosuppressive agents, which are associated with significant risk of adverse events.

The limitation of western medicine has prompted increasing number of patients to turn to TCM [4], in part due to the perceived safety of TCM by patients and in part due to the appeal of pedagogy of TCM in restoring balance and potentially curing the disease.

However, the complexities of herbal decoctions and granules, the different routes of administration, and auxiliary treatments such as acupuncture and massage have proven daunting for western doctors to regard TCM with any amount of credibility. It also does not help that early studies were mainly found in Chinese publications, thus reducing accessibility. With the need for more objective evidence and validation, TCM is now being extensively studied in clinical trials and pharmacological studies.

Herbs [3] such as Cortex Moutan Radix (Danpi), Radix Paeoniae Alba (Bai Shao), Potentilla chinensis Ser (Weilingcai), and Radix Glycyrrhizae (Gan Cao) are common treatments for allergy. Flos Lonicerae (Jinyinhua) and Herba Menthae (Bohe) clear ‘damp-heat’ from the exterior; Cortex Moutan (Danpi) clears ‘heat’ from blood while Rhizoma Atractylodis (Cangzhu) and Cortex Phellodendri (Huangbai) clear the ‘damp-heat’ from the interior. Pharmacological studies indicate that these herbs have anti-allergic, anti-inflammatory, and sedative action for relief of itchiness.

To date there are seven randomized controlled trials [6] (one comparing Chinese herbal medicine and western medicine with western medicine alone; six comparing Chinese herbal medicine with placebo) and more than 200 clinical trials investigating the efficacy of TCM in AD.

Cheng et al. [7] studied the efficacy of a common herbal preparation Xiao Feng San (comprising of Glycyrrhiza uralensis (Gancao), Saposhnikovia Divaricate (Fangfeng), Schizonepeta tenuifolia (Jingjie), Atractylodes lancea (Cangzhu), Angelica sinensis (Danggui), Rehmannia Glutinosa (Dihuang), Clematidis Armandii (Chuanmutong), Cryptotympana pustulata (Chantui), Linum usitatissimum (Yamazi), Anemarrhena asphodeloides (Zhimu), Gypsum Fibrosum (Shigao), Sophora flavescens (Kushen), Articum lappa (Niubangzi)) commonly used in the Asian context for the treatment of AD. In a double-blind, randomized control trial of 71 patients (8–23 years) with severe AD affecting >20 % body surface area, there were statistically significant improvement in pruritus, erythema, surface damage, and sleep scores. No side effects were experienced in all the patients, suggesting that TCM would be a potentially beneficial and safe adjunctive therapy for patients with recalcitrant AD.

Huang et al. [8] found a combination of western medicine and TCM to be superior to western medicine alone in children aged 3–11 years, in improving clinical scores. Shi et al. [9] demonstrated that the TCM Jiawei Danggui decoction improved AD scores through modulation of inflammatory cytokines such as IL-4, IL-10, and IL-12. More recently, an open-label clinical study [10] involving a novel combination of oral and topical TCM therapy in 94 patients showed significant improvement in severity of AD. Serum IgE level and eosinophil counts were significantly reduced at the end of the study.

Two randomized placebo-controlled trials [11, 12] were performed to study the effects of Zemaphyte, a decoction of ten herbs useful for treating AD characterized by erythema, lichenification, and plaques of dermatitis in the absence of active exudation or clinical infection. The ten herbs used were Lophatherum gracile (Danzhuye), Potentilla Chinensis (Weilingcai), Tribulus terrestris (Jili), Rehmannia glutinosa (Dihuang), Clematidis armandii (Chuanmutong), Ledebouriella Saseloides (Fangfeng), Dictamnus dasycarpus (Baixianpi), Paeonia lactiflora (Baishao), Schizonepeta tenuifolia (Jingjie), and Glycyrrhizia Glabra (Gancao). These herbs were placed in sachets and boiled to make a decoction that was orally administered daily as a tea. The placebo consisted of a decoction made from several herbs with similar smells and tastes that have no known efficacy in AD. The first study involving 47 children demonstrated a median decrease in erythema score of 51 %, in the treatment group compared with only 6.1 % improvement in the placebo group. The percentage surface involvement also decreased by 63.1 % and 6.2 % for the herb-treated and placebo groups, respectively. No serious adverse effects were found. These children were offered continued treatment, with 18 children completing 1 year of treatment and showed 90 % reduction in eczema activity scores. By the end of 1 year, seven children were able to discontinue therapy without relapse. Asymptomatic elevation of alanine aminotransferase level was noted in two patients, levels returning to normal after discontinuing treatment. Although the sample sizes were limited, results were promising for patients with persistent disease. It should be emphasized that although no serious adverse effects were noted in this study [10], careful monitoring of complete blood cell count and liver function is recommended, as liver failure and even death have been reported with these TCM herbs. However, in a separate study [13] involving 40 patients, investigators did not observe any benefit of Zemaphyte in recalcitrant AD. So far, the sample sizes of these studies are too limited for any real conclusion to be made, and more robust studies are required.

PentaHerbs a proprietary capsule comprising of five different herbs, Paeonia suffruticosa root bark (also known as Cortex Moutan), Phellodendron Chinensis bark (Chuanghuangbai), Lonicera japonica flower (Jinyinhua), Mentha Herba aerial part (Bohe), and Atractylodes lancea rhizome (Cangzhu), was found, in a randomized, double-blind, placebo-controlled study [14], to have beneficial effects on improvement of eczema SCORAD and Children Dermatology Life Quality Index (CDLQI) scores. The use of topical steroid [15] was also reduced by one-third. However, no significant difference in overall clinical scores was found. The PentaHerbs formulation was tested for contaminants [16] such as heavy metals or corticosteroid and found not to contain any. In a separate study [17], the herbal formula, Hochu-ekki-to (comprising of Radix Astragali (Huangqi), Panax Ginseng (Renshen), Rhizoma Atractylodis (Cangzhu), Glycyrrhiza uralensis (Gancao), Angelica sinensis (Danggui), Citri Reticulatae (Baomazipi), Rhizoma Cimicifugae (Shengma), Radix Bupleuri (Chaihu), Zingiber Officinale (Jiang), Fructus Jujubae date (Dazao)) was found to reduce the total equivalent amount of topical corticosteroid usage by 50 % during a 6-month period in a multicentre, randomized, double-blind, placebo-controlled study. However, again there was no statistically significant difference in skin severity scores.

It is important to note that the combinations of herbs used in the various studies were different, giving rise to different pharmacokinetics and pharmacodynamics. There are also concerns that the varied geographic sources of the herbs used in different studies could also have affected the active compounds. Therefore, more RCTs and rigorous pharmacological studies are necessary for stronger evidence regarding efficacy of TCM.

It is known that the specific herbs [18–20] used in these studies have anti-inflammatory, antibacterial, antifungal, antihistaminic, immunosuppressant, and corticosteroid-like effects. Several studies have attempted to elucidate the mechanism of action of individual herbs and their combined effects.

Oral administration of Gypsum fibrosum was shown to increase cutaneous water content in mice [18] via the upregulation of aquaporins. Gypsum fibrosum is a common TCM herb given to relieve “heat,” characterized by excessive thirst, sweating, fatigue, poor concentration, pruritus, and dry skin, in the body.

Bakumijiogan, a unique TCM herbal formula, comprising of eight herbs, Rehmannia Radix (Dihuang), Cornus Fructus (Shanzhuyu), Dioscoreae Rhizoma (Shanyao), Alisma Rhizoma (Zexie), Poria Sclerotium (Fushen), Moutan bark (Mudanpi), Ophiopogon japonicus tuber (Maidong), Schisandra chinensis fruit (Wuweizi), was shown to reduce swelling of AD lesions [21] in Nishiki Nezumi Cinnamon (NC) mouse models. This effect was attributed to the downregulation of the T-helper 2 cytokines, namely interleukin-1α (IL-1α) and tumor necrosis factor TNF-α.

PentaHerbs is a formula comprising of five different herbs, which were individually assessed for their effects on mast cell activity. Each herb was found to have various modulating effects on mast cells [18], which included the inhibition of histamine release from mast cells and prostaglandin D2 synthesis. PentaHerbs decreased plasma levels of brain-derived neurotrophic factor (BDNF) and thymus and activation-regulated chemokine (TARC) in children with AD. PentaHerbs suppressed mRNA transcription of BDNF, TARC, interferon-γ, and tumor necrosis factor-α [19] by cultured peripheral blood mononuclear cell (PBMC). These immunomodulatory properties are believed to contribute to the clinical efficacy in AD treatment.

The bark of the birch tree (Betula platyphylla var. Japonica) which is used to treat AD, was studied in NC/Nga mice models [21] for AD. The herb decreased scratching and skin inflammation, as well as immunoglobulin E and interleukin-4 messenger ribonucleic acid (mRNA) levels. The findings suggest that the herb exerts some effect on the suppression of the T-helper 2 cellular response in AD. In the Zemaphyte trials [22], biopsy specimens were obtained from the lesional skin of patients treated with the herbal combination. The investigators observed a statistically significant reduction in CD23 antigen-presenting cells, compared with nonlesional skin.

Indigo Naturalis (Qingdai) [23], a dark-blue powder prepared from the leaves of plants such as Baphicacanthus cusia, Polygonum tinctorium, Isatis indigotica and Indigofera tinctoria, exhibits antiviral, antibacterial, and antitumor properties. It is used in treatment of various inflammatory and infectious diseases, e.g., eczema, aphthae, erysipelas, and herpes zoster. Due to its apoptotic effect [24] and ability to modify the proliferation and differentiation of keratinocytes, it is commonly employed in the treatment of psoriasis. Moreover, indirubin [24], one of the active compounds, has been shown to inhibit the production of interferon-γ, interleukin-6, and RANTES chemokine, involved in psoriasis pathogenesis.

Radix Salvia Miltiorrhiza (Danshen) [25] contains a variety of deterpenoids, phenolics, flavonoids, triterpenoids, and sterols. Its active components have anti-ischaemic, antioxidant, and antitumor activity. It has a significant inhibitory effect on the production of IFN-γ from lymphocytes and IL-12 from macrophages as well as suppression of mast cell degranulation. This herb is thought to exhibit some hepatoprotective effect [26], which is in part due to its ability to improve blood circulation and promote regeneration of liver cells.

Glycyrrhiza uralensis (Gancao) [27], may have protective effect on hepatocytes and gastrointestinal tract, is commonly used as component of various antipsoriatic and anti-eczema preparations. It is believed to prevent side effects commonly observed in the process of herbal therapy application. Moreover, it exerts both immunosuppressive and immune-enhancing activities, which may modulate abnormal immunological processes in eczema. Rehmannia glutinosa (Dihuang), a frequent ingredient in herbal formulas, is a Chinese herb use in the treatment of eczema and psoriasis and various dermatoses. In animal models [28], the root of Rehmannia glutinosa is capable of inhibiting the release of histamine and production of TNF-α and IL-1, and therefore having a positive effect on the treatment of eczema and psoriasis.

Radix Angelicae (Danggui) [29] is regarded as an effective agent in treatment of acne, headache, toothache, sinusitis, colds, and flu. It contains furocoumarins [30], actively involved in the inhibition of cyclooxygenase and lipoxygenase pathways of arachidonate metabolism. Since Angelica species are sources of psoralens, they are applied both systemically and topically in psoriasis. The herb is capable of inducing phototoxic reactions in some individuals.

TCM as an adjunctive treatment [31] has been reported to benefit the patients with several other dermatological conditions such as alopecia totalis, Behcet’s disease, psoriasis, and scleroderma (Fig. 47.1).