Azithromycin for viral bronchitis - case report and analysis
Donald Harvey. Marks, M.D., Ph.D.
Emeritus Fellow, American College of Physicians
26-3-2026
A pulmonary doctor opted to prescribe a novel treatment for presumed viral (parainfluenza 6) bronchitis - azithromycin. This was in addition to corticosteroids and bronchodilators via nebulizer. The 75 year old male nonsmoking patient was without symptoms of a bacterial (fever, productive cough) respiratory infection, had an unremarkable CXR
, but had a recent hospitalization 3 months prior for documented viral (RSV and influenza A) bronchitis, and a 3-vessel CABG 10 months previously. The rationale for prescribing azithromycin was for possible anti-inflammatory properties which could be therapeutically beneficial to the recovery from the viral bronchitis. What is the basis for this reasoning?
Azithromycin, while primarily known as a macrolide antibiotic used to treat bacterial infections, has been increasingly recognized for its anti-inflammatory and immunomodulatory effects, particularly in chronic respiratory diseases like:
Chronic obstructive pulmonary disease (COPD)
Asthma
Diffuse panbronchiolitis
Cystic fibrosis
The purported anti-inflammatory and immunomodulatory effects of azithromycin appear to be independent of its antibacterial action and are thought to be mediated by:
Inhibition of neutrophil migration and activation,
Reduction of pro-inflammatory cytokines like IL-6, IL-8, and TNF-α,
Stabilization of epithelial cell barriers and mucosal immunity,
Suppression of bacterial virulence factors and biofilm formation (indirectly reducing inflammation from colonizing organisms)
Beyond its antibacterial action, azithromycin has been shown to:
Modulate immune responses: It can shift macrophages toward an anti-inflammatory phenotype and reduce the production of pro-inflammatory cytokines like IL-6 and TNF-α. (Poĺlock 2021),
Enhance phagocytic activity: Azithromycin improves the ability of alveolar macrophages to clear apoptotic cells, aiding in the resolution of inflammation (Hodge 2006),
Inhibit key inflammatory pathways, by suppressing the NF-κB signaling pathway, which plays a central role in the inflammatory response.
Evidence in Acute Viral Bronchitis
When it comes to therapeutic efficacy for treating acute viral bronchitis, the evidence supporting azithromycin is much thinner. Several meta-analyses and randomized controlled trials have concluded that antibiotics offer little or no benefit in otherwise healthy patients with viral bronchitis. Still, some pulmonologists might use azithromycin empirically in:
Patients with comorbidities (e.g., chronic lung disease, but not present in this case)
Evidence of secondary bacterial infection {but not present in this case}
Cases where inflammatory symptoms are persistent or severe.
One study often cited in this context is Kanoh & Rubin (2010), which supported the idea that azithromycin may suppress inflammation even in non-bacterial lung disease.
Application in Viral Bronchitis
While azithromycin is not typically indicated for viral infections, its anti-inflammatory properties have been explored in this context. For instance, a study demonstrated that azithromycin treatment in a mouse model of viral bronchiolitis led to reduced airway inflammation and improved disease outcomes. Beigelman et al(2010) investigated the effects of azithromycin on airway inflammation in mice infected with parainfluenza type 1, Sendai Virus (SeV). They found that azithromycin significantly reduced post-viral weight loss, leukocyte accumulation, and inflammatory mediators, leading to improved disease outcomes.
Bottom Line
The pulmonologist’s reasoning has a scientific basis, especially considering the patient’s age, cardiac history, and pulmonary comorbidities. While it wouldn't be appropriate for every patient with viral bronchitis, in this case, the potential anti-inflammatory and immunomodulatory properties of azithromycin may offer some benefit in modulating airway inflammation, possibly speeding symptom resolution or preventing complications.
Considering the patient’s unique medical background and the severity of symptoms, the pulmonologist might have opted for azithromycin to leverage its anti-inflammatory benefits, aiming to alleviate airway inflammation and prevent potential complications.
The addition of azithromycin, at least in this case, was a bit nuanced and not universally accepted, but certainly justified. In the end, the azithromycin in this particular case was not beneficial and did not reduce the symptoms of chronic viral bronchitis, particularly coughing.
References
Beigelman A, Mikols CL, Gunsten SP et al. Azithromycin attenuates airway inflammation in a mouse model of viral bronchiolitis. Respir Res 11, 90 (2010). https://doi.org/10.1186/1465-9921-11-90
Hodge S, Hodge G, Brozyna S. Azithromycin increases phagocytosis of apoptotic bronchial epithelial cells by alveolar macrophages. European Respiratory Journal 2006 28(3): 486-495
Hodge S, Hodge G. Azithromycin Improves Macrophage Phagocytic Function and Expression of Mannose Receptor in Chronic Obstructive Pulmonary Disease | American Journal of Respiratory and Critical Care Medicine Volume 178, Issue 2, 2008.
Huang D, Xie L, Luo T et al. Effects of azithromycin on alleviating airway inflammation in asthmatic mice by regulating airway microbiota and metabolites. Microbiol Spectr. 2025 Mar 4;13(3):e0221724. doi: 10.1128/spectrum.02217-24.
Kanoh S, Rubin BK (2010). Mechanisms of action and clinical application of macrolides as immunomodulatory medications. Clinical Microbiology Reviews, 23(3), 590–615. https://doi.org/10.1128/CMR.00078-09
Ling KM, Hillas J, Lavender MA et al. Azithromycin reduces airway inflammation induced by human rhinovirus in lung allograft recipients. Respirology. 2019 Dec;24(12):1212-1219. doi: 10.1111/resp.13550.
Pollock J, Chalmers JD. The immunomodulatory effects of macrolide antibiotics in respiratory disease: Pulm Pharmacol Ther . 2021 Dec:71:102095. doi: 10.1016/j.pupt.2021.102095.
Yan Y, Wu L, Li X et al. Immunomodulatory role of azithromycin: Potential applications to radiation-induced lung injury. Front Oncol. 2023 Mar 8;13:966060. doi: 10.3389/fonc.2023.966060
