Background: Zingiber cassumunar Roxb., frequently known as Phlai in Thai, has been safely used as an antihistaminic and anti-inflammatory drug in Thai traditional medicine. Individual with allergic rhinitis may have positive response to Phlai.

Objective: Investigators assessed the efficacy and safety of Phlai as a treatment for allergic rhinitis Design: The study was a 1-month, double-blind, randomized, parallel-group, intent-to-treat, multicenter, controlled trial in 267 patients at 7 hospitals in Thailand. Skin prick test-positive adults with allergic rhinitis ages 18 to 50 who were randomized into 3 groups (Phlai 8mg/d, Phlai 4mg/d, placebo).

Main outcome measures: Primary outcome was defined: improvement of total 5 symptoms scores (nasal obstruction, rhinorrhea, sneezing, itchy nose, itchy eyes) over a 4-week interval among Phlai 8mg/d, Phlai 4mg/d and placebo. Secondary endpoints were: assessments of rhinoconjunctivitis quality of life questionnaire, peak inspiratory nasal flow, nasal examination, adverse events, AST, ALT, Creatinine and BUN over a period of 4 weeks.

Inclusion Criteria:

• Age 18-50 years old
• Allergic rhinitis following diagnostic criteria of ARIA guideline
• Reflective total 5 symptoms score 2-10 per day for 3 consecutive days (total score=15) and not greater than 10 in any days during the past week
• Positive skin prick test to at least one aeroallergen: wheal size ≥ 3 mm greater than negative control
• Not receiving intranasal corticosteroid + intra antihistamine for 2 weeks , intranasal corticosteroid for 2 weeks, systemic corticosteroid for 4 weeks, antihistamine for 1 week, nasal decongestant for 1 week and leukotriene receptor antagonists for 1 week

Exclusion Criteria:

• Serious medical underlying diseases e.g. COPD, Heart disease, Chronic renal failure, chronic hepatic failure
• Allergic rhinitis and asthma which require immunotherapy
• Receiving antidepressants, sedative, anxiolytic, opioids, neuroleptic
• Uncontrolled asthma which requires steroid inhaler, LABA and does not use leukotriene receptor antagonists
• Previous nasal surgery for nasal polyp, nasal septum deviation
• Acute or chronic rhinosinusitis
• Pregnancy and lactation (Urine pregnancy test is allowed and paid by researchers)
• Allergic to any kinds of herb
• Refusal to participation

Will plan to share information when finishing study

Plan to complete study in 2 years and will share the data after get publication

Participant, care provider and investigator, outcomes assessor in each site do not know what kind of medication in each package.