You can add honey with or instead of ginger.

Evaluations of thyme extract effects in human normal bronchial and tracheal epithelial cell lines and in human lung cancer cell line – PubMed.gov: https://www.ncbi.nlm.nih.gov/pubmed/27369807

– Efficacy and tolerability of a fluid extract combination of thyme herb and ivy leaves and matched placebo in adults suffering from acute bronchitis with productive cough. A prospective, double-blind, placebo-controlled clinical trial– PubMed.gov: https://www.ncbi.nlm.nih.gov/pubmed/17063641/

– Cough medicines are a waste of money admits NHS – Independent: http://www.independent.co.uk/life-style/health-and-families/health-news/cough-medicines-a-waste-of-money-admits-nhs-9798049.html

Les sirops contre la toux ne servent à rien – Nouvel Obs: https://www.nouvelobs.com/sante/20151021.OBS8048/les-sirops-contre-la-toux-ne-servent-a-rien-pour-la-plupart.html