Efficacy and safety of herbal medicines for relief cough symptom in national list of essential medicines of Thailand and Lao PDR: A systematic review and Meta-analysis

Abstract

Introduction: cough is the common symptom of the respiratory tract infections or non-infections, the duration of cough indicates a classification and severity of the disease. Herbal medicines can be used as the alternative to drugs for relief of cough symptoms from acute and chronic disease. herbs were used for reducing cough but lack of evidence to confirm their efficacy and safety. The present study aims to evaluate the efficacy and safety of herbal medicines for the relief of cough symptom in the national essential drug list of Thailand and Lao PDR.

Method: the studies were searched in the Cochrane Library, PubMed, Scopus, CINAHL, Springer, Science Direct, ProQuest, and THAILIS databases. we searched from its inception until 01/02/2019 for randomized control trials. We followed for the efficacy and safety of herbs for reducing cough. Methodological quality was evaluated by using the Cochrane risk of bias tool; two reviewers in our team screened eligibility and extracted data.

Result: Twenty studies were included for the review and seventeen studies were included in the meta-analysis, there were 4,098 persons and age between 1 and 80 years old. Four herbs in the studies including eucalyptus (n: 6), honey (n: 10), ginger (n: 3) and Malabar nut (n: 2) studies. Overall of the risk of bias included trial, we found poor in missing outcome data. Ten of 20 included study were the effect on cough in children and eleven studies in adult. All four herbs were used as a pure herb (n: 7) and in combination with mixture herbs (n: 14). All of the studies with herbs were compared for efficacy and safety with placebo or standard treatment. Dosage form in studies included syrup (n:11), capsules (n: 9), and spray (n:1). Most of the included studies found that eucalyptus and honey, ginger, and mabala-based preparations were superior to placebo and no difference with active control in reducing cough symptom and improve quality of life. This meta-analysis supports these findings and shows that eucalyptus reduce overall cough score small heterogeneity (I2 = 1.2%, χ2 = 1.01; P-value = 0.314). The efficacy of eucalyptus was found a statistically significant (n = 402, RR: 1.40, 95%CI [1.19, 1.65], P-value < 0.0001) when compared with placebo. The effect of honey compared placebo statistic significantly in all cough symptom (n = 3252, SMD: -0.63, 95%CI [-0.85 to -0.40], I2 =0 %, P<0.0001). Honey compared active control or standard treatment the data shown overall effective of cough statistic no significant all studies included P=0.07 (n=3111, SMD: -0.29, 95%CI [-0.60 to 0.02], I2 =93 %, P<0.0001). Ginger and malabar nut were good effects for cough symptom URI, COPD and asthma. however, these herbs will need evidence to support this respect. The AES showed no statistic difference between treatment and control group.

Conclusion: This review found four herbs from 30 herbs essential national drug list in Thailand and Lao PDR including eucalyptus, honey, ginger, and malabar nut. Eucalyptus and honey were positive effects than placebo in alleviating the overall symptom of patients’ cough and improved patient quality of life. The better positive effect when we compared with standard treatment was found a similar effect. We suggest this herbal medicine may be recommended as an adjunct to conventional medicine. The effect reduces cough symptom of ginger and malabar nut will need evidence to support this respect. Additional research, including other herbal treatments, is needed in this area.

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