Epithelial barrier dysfunction is involved in the pathogenesis of allergic disorders, such as nasal allergy. TWIK-related K(+) 1 (Trek1) potassium channels are required in the maintenance of the epithelial barrier function. This study aims to investigate the role of antigen-specific immunotherapy (SIT) in the regulation of Trek1 expression in the nasal mucosa. In this study, patients with nasal allergy were treated with SIT and/or Clostridium butyricum. The expression of Trek1 and histone demethylase 1 (HDAC1) in the nasal epithelia was assessed by real-time reverse transcription polymerase chain reaction and Western blotting. Serum cytokines were assessed by enzyme-linked immunosorbent assay. The results showed that Trek1 and HDAC1 were detected in the nasal epithelia. Trek1 was lower, whereas HDAC1 was higher in patients with allergic rhinitis as compared with healthy controls. Trek1-null RPMI2650 monolayers showed a markedly compromised epithelial barrier function. Treatment with SIT significantly increased the Trek1 levels in the nasal epithelia of allergic rhinitis patients that were further improved in conjunction of SIT and administration of probiotic C. butyricum. In conclusion, nasal epithelia express Trek1 that can be suppressed by allergic response. SIT can restore the expression of Trek1 in the nasal epithelia and can be further improved by conjunction with administration of C. butyricum. Copyright (c) 2014 John Wiley & Sons, Ltd.