With the increased inclination towards herbal medicine in recent years, they have been exploited for the treatment of various diseases. Randive D. S. et al formulated and evaluated a herbal cough syrup from the petal extracts of Calendula officinalis L., which utilized its petal extract, honey and distilled water. The formulation was evaluated in terms of pH, colour, odour, taste, thermal stability, turbidity, accelerated stability studies, HPTLC and antimicrobial activity against different microbial strains namely Aspergillus niger, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus and E. coli. 

They found that the aqueous extract of C. Officinalis exhibits good antimicrobial activity against the selected microbial strains, and can be used for the treatment of cough. The addition of honey made it more soothing and sweet.

Source: Randive DS, Bhinge SD, Bhutkar MA, Joshi SR, Patil PD, Shejawal KP, Thorat MS, Mulla AS. Formulation And Evaluation Of Herbal Cough Remedy From Extract Of Calendula Officinalis L. Indian Drugs, 2020;7(4):52-58.