Twenty-nine (29) studies involving 3,001 participants were included. Herbal interventions used multi-ingredients such as licorice root, crow-dipper, astragali, and angelica. Compared with routine pharmacotherapies alone, herbal medicines as add-on therapy improved lung function; asthma control; reduced salbutamol usage; and reduced acute asthma exacerbations over one year. Compared with placebo plus pharmacotherapies herbal medicines as add-on therapy improved lung function. Other outcomes were not reported in these placebo studies. Included studies were low to moderate quality. Adverse events were rare.