Evaluation of shoseiryuto for seasonal allergic rhinitis, using an environmental challenge chamber.

Background: Complementary and alternative medicine, including Japanese traditional medicine (JTM), has been used for various allergic diseases, but the evidence is limited. Shoseiryuto (Xiao-Qing-Long-Tang), one of the representative JTM drugs, is frequently used to treat allergic rhinitis (AR). However, its efficacy for seasonal AR has not been fully established. Using an Environmental challenge chamber (ECC), we evaluated the therapeutic effects of shoseiryuto on AR induced by Japanese cedar pollen (JCP).

Methods: A placebo-controlled double-blind crossover study with shoseiryuto was conducted using the ECC. The shoseiryuto or placebo was orally administered from 2 weeks before the exposure test. The pollen exposure test was conducted for 3 h, and the pollen concentration was set at 8000 pollen/m. The primary endpoint of the study was the total nasal symptom score (TNSS) during pollen exposure. A physician certified by the Japanese Society of Oriental Medicine as a specialist checked each participant's "pattern", a comprehensive expression of signs obtained from individual patients' subjective symptoms and other personal findings. Blood samples collected just before the first pollen exposure were stimulated with cedar antigens and used for immunological studies.

Results: The results of the 46 participants were analyzed, and no significant side effects were detected. There was no significant difference in TNSS during pollen exposure for 3 h in the ECC between the shoseiryuto and placebo groups. However, some symptoms were improved in the shoseiryuto group after leaving the ECC. There was no significant correlation between the "fluid retention pattern" and TNSS. In immunological studies, shoseiryuto did not inhibit Th2-type cytokine production and mRNA expression.

Conclusions: Oral administration of shoseiryuto from 2 weeks before pollen exposure did not prevent or inhibit immediate symptoms of AR induced by JCP in the ECC. Further study is needed to reevaluate the shoseiryuto specific "pattern" in JTM.