Effect of Hyssop (Hyssopus officinalis) Syrup on Mild to Moderate Asthma: A Randomized Double-Blind Placebo-Controlled Trial

Asthma is one of the most common respiratory diseases. Hyssopus officinalis L. is a medicinal herb that has shown anti-asthmatic effects and has also been recommended in Persian Medicine literature for its treatment. In this study, the efficacy of hyssop in mild to moderate asthma was investigated considering the patients' phenotype (having productive/non-productive cough).

In a randomized triple-blind placebo-controlled trial, 60 mild-to-moderate asthmatic patients were randomized to receive either hyssop syrup (5 ml twice daily containing 6g Hyssopus officinalis L. extract) or plain sugar syrup (5 ml twice daily) for 4 weeks as an adjuvant to routine treatment. Outcome measures were the Asthma Control Test (ACT), pulmonary function tests, Expert Panel Report 3 (EPR3), and wheezing severity.

The patients with productive cough in the hyssop group showed significant improvement in forced expiratory volume in 1 second (FEV1), ACT (at the 4th week), peak expiratory flow (PEF), maximal expiratory flow rate 25-75 (MEF25-75%), and wheezing severity. However, those with dry cough got worse regarding these indices.

Hyssop syrup is effective for asthmatic patients with productive cough and a higher BMI, but it is not suitable for those experiencing a dry cough. It highlights the importance of syndrome differentiation in asthmatic patients and a posteriori subgrouping in data analysis. This approach enhances treatment accuracy and response rates while reducing adverse effects. Future trials are guaranteed to approve this categorization in asthma treatment.