The effects of two Chinese herbal medicinal formulae vs. placebo controls for treatment of allergic rhinitis : a randomised controlled trial

Abstract

Background: Allergic rhinitis is a chronic illness, affecting 10 to 40% of the worldwide population. Chinese herbal medicines, the treatment of allergic rhinitis, adopted thousands of years in ancient China, has recently raised much attention among researchers globally. This study evaluates the effects of two Chinese herbal formulae [Cure-allergic-rhinitis Syrup (CS) and Yu-ping-feng San (YS)] in treating undergraduate nursing students with allergic rhinitis over a 3-month follow-up, when compared to a placebo control group. Methods: A double-blind, randomised controlled trial with repeated-measures, three-parallel-groups design was conducted in a random sample of 249 participants recruited from one university in Hong Kong. After baseline measurements, participants were randomly assigned to CS, YS, or placebo groups (n = 83 per group). The main outcomes, including symptom severity, quality of life, and body constitution, were measured with self-administered questionnaires at baseline and immediately, 1 and 3 months after the 4-week interventions. Results: 240 participants completed the trial, with 9 (3.6%) drop-outs. The results of Generalised Estimating Equations test followed by pairwise contrasts tests indicated that the participants who received CS showed significantly greater reduction of symptoms (mean difference of CS vs. placebo = 26.13-34.55, P < 0.0005) and improvements in quality of life (mean difference of CS vs. placebo = 12.81-16.76, P < 0.001), and body constitution in 'Qi- deficiency', 'Yang-deficiency', and 'Inherited Special' (mean difference of CS vs. placebo = 7.05-8.12, 7.56-8.92, and 4.48-8.10, P = 0.01- < 0.0005, 0.001-0.004, and 0.01- < 0.0005, accordingly, at three post-tests). The participants who received YS also indicated significant greater improvements in symptom severity, quality of life, and a few patterns of body constitution when compared to the placebo group. However, its effects were lesser in strength (i.e., smaller effect sizes), varieties of symptoms, and body constitution and sustainability over the 3 months. Conclusions: The herbal formula CS was found effective to reduce symptoms and enhance quality of life in young adults (nursing students) with allergic rhinitis in 'Yang- and/or Qi-deficiency' body constitution. Further controlled trials of its effects in Chinese and/or Asians with allergic rhinitis in terms of socio-demographic, ethnic and illness characteristics and a longer-term follow-up are recommended.