RCT-evidence for drug efficacy | Subjective clinical symptoms | Objective cough recording | Cough challenge | Remarks |
---|---|---|---|---|
Codeine | − | − | − | No convincing evidence of efficacy |
Dextromethorphan | + | + | ++ | Well characterised in objective studies |
Pentoxyverine | − | − | − | Only animal studies via 3 clinical studies >50 years old |
Butamirate | − | − | − | No placebo-controlled study published |
Levodropropizine | + | − | + | 6 short-term placebo or active comparator controlled studies n=174 |
Ambroxol | + | − | − | Many additional non-interventional studies |
N-acetylcysteine | Children + Adults − | − | − | Many studies for COPD, chronic cough, antioxidant properties |
Oxomemazine | − | − | − | Only observational studies |
Menthol | − | − | + | Widely used. Vapour antitussive via TRPM8 |
Helicidine | − | − | − | No clinical evidence of efficacy in acute cough |
Diphenhydramine | − | − | − | Broad clinical use |
COPD, chronic obstructive pulmonary disease; RCT, randomised controlled trial.