Clinical trial, with positive findings,  on 217 patients with bronchitis who were treated at doctors’ practices  in Germany. Approximately half of the patients were randomly allocated  to receive a combination homeopathic medicine called Bronchiselect, and  the others received a dummy pill (placebo); they were not told which  treatment group they were in. After 3 weeks of treatment, the patients  receiving homeopathy had fewer days of coughing than the patients  receiving placebo.

Diefenbach M, Schilken J, Steiner G, Becker HJ (1997). Homöopathische  Therapie bei Erkrankungen der Atemwege. Auswertung einer klinischen  Studie bei 258 Patienten [Homeopathic therapy in respiratory tract  diseases. Evaluation of a clinical study in 258 patients]. Zeitschrift  für Allgemeinmedizin; 73:308–314.