Disease processes encompassed by the term bronchiolitis
| Infectious | Toxic | Autoimmune | Cryptogenic/miscellaneous |
| Respiratory viruses, such as the respiratory syncytial virus, influenza and parainfluenza | Smoke-related and e-cigarette or vaping use-associated lung injury (EVALI) | Bronchiolitis obliterans syndrome (BOS) seen in chronic lung allograft dysfunction | Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) |
| Parasitic | Diffuse aspiration bronchiolitis | Sjögren syndrome | Langerhans histiocytosis |
| Fungal | Nitrogen dioxide (NO2) inhalation | Paraneoplastic | Follicular bronchiolitis |
| Mycobacterial | Mustard gas (sulfur mustard) | Rheumatoid arthritis | Panbronchiolitis |
| Mycoplasma pneumoniae | Ingestion of Sauropus androgynus | Systemic lupus erythematosus | Eosinophilic bronchiolitis |
| Allergic bronchopulmonary mycosis | Diacetyl (popcorn plant workers) | Inflammatory bowel disease-related bronchiolitis | COPA syndrome |
Information from [8–11].