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Randomized Controlled Trial
. 2025 Jul 1;25(1):830.
doi: 10.1186/s12879-025-11194-w.

Efficacy and safety of inhaled ambroxol hydrochloride solution in patients with lower respiratory tract infectious diseases: a randomized, double-blind, placebo-controlled, multicentre clinical trial

Di Wu  1 , Xiuhua Fu  2 , Faguang Jin  3 , Hui Li  4 , Zhiqiang Qin  5 , Haoyan Wang  6 , Hongmei Yue  7 , Jie Zhang  8 , Zhaolong Cao  9
Affiliations
Randomized Controlled Trial

Efficacy and safety of inhaled ambroxol hydrochloride solution in patients with lower respiratory tract infectious diseases: a randomized, double-blind, placebo-controlled, multicentre clinical trial

Di Wu et al. BMC Infect Dis. .

Abstract

Background: Ambroxol is a widely used mucoactive agent, but the efficacy of inhaled ambroxol in patients with lower respiratory tract infectious (LRTI) disease is poorly understood. This trial aimed to compare the efficacy and safety of inhaled ambroxol with those of placebo in patients with LRTI diseases.

Methods: In this randomized, double-blind, placebo-controlled, multicentre clinical trial, 240 patients with LRTI diseases were randomized to receive inhaled ambroxol hydrochloride solution (ambroxol group, N = 120) or placebo (placebo group, N = 120) twice daily for 7 days.

Results: Compared with the placebo group, the ambroxol group had lower sputum trait scores and greater changes in sputum trait scores from Day 2 to Day 8. Compared with the placebo group, the ambroxol group presented lower expectoration difficulty scores and greater changes in expectoration difficulty scores on Days 2, 3, and 6. The sputum volume scores on Days 6, 7, and 8 were lower in the ambroxol group than in the placebo group, but the change in the sputum volume score was not different between the groups. Compared with the placebo group, the ambroxol group had lower cough scores on Days 3, 5, 6, and 7, as well as greater changes in cough scores on Days 2, 3, and 5. The incidences of adverse events (10.8% versus 6.7%), serious adverse events (0.8% versus 0.0%), and adverse reactions (4.2% versus 3.3%) were not different between the ambroxol group and the placebo group.

Conclusions: Inhaled ambroxol is better at ameliorating respiratory symptoms and has comparable safety to placebo in patients with LRTI diseases.

Keywords: Ambroxol; Efficacy; Inhalation; Lower respiratory tract infectious diseases; Safety.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Patients signed the informed consent. The Ethics Committee of Peking University People’s Hospital approved the trial with the Ethics number of 2013-21. The trial was registered on Chinese Clinical Trial Registry with the number of ChiCTR2300072467. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
A flow diagram
Fig. 2
Fig. 2
Sputum trait comparison between the ambroxol and placebo groups. Comparison of sputum trait scores (A) and changes in sputum trait scores (B) between groups. Data were presented as mean with standard deviation
Fig. 3
Fig. 3
Expectoration difficulty comparison between the ambroxol and placebo groups. Comparison of expectoration difficulty scores (A) and changes in expectoration difficulty scores (B) between groups. Data were presented as mean with standard deviation
Fig. 4
Fig. 4
Sputum volume in the ambroxol and placebo groups. Comparison of the sputum volume score (A) and change in the sputum volume score (B) between the groups. Data were presented as mean with standard deviation
Fig. 5
Fig. 5
Cough in the ambroxol and placebo groups. Comparison of cough scores (A) and changes in cough scores (B) between groups. Data were presented as mean with standard deviation
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