Sweet Violet (Viola odorata) and Asthma: evidence and sources

This study aimed to investigate the effect of violet syrup on cough alleviation in children with intermittent asthma. In a parallel, double-blind, randomized controlled trial, 182 children aged 2 to 12 years with intermittent asthma were randomly assigned 1:1 to receive violet syrup or placebo along with the common standard treatments in both groups (short-acting β-agonist). Both groups were evaluated in terms of the duration until cough suppression was achieved. No significant difference was observed in basic characteristics. The duration lasting to yield more than 50% cough reduction and 100% cough suppression was significantly less in the violet syrup group compared to placebo (P = .001, P < .001, respectively). There was no significant difference in therapeutic effects between boys and girls. There was a significant inverse correlation between the age of children and rate of cough alleviation and suppression by violet syrup. This study showed that the adjuvant use of violet syrup with short-acting β-agonist can enhance the cough suppression in children with intermittent asthma.