Common aetiologies of asthma exacerbations
| Virus induced | Rhinovirus (RV) |
| Respiratory syncytial virus (RSV) | |
| Human metapneumovirus (HMV) | |
| Influenza virus | |
| Bacteria induced | Mycoplasma pneumoniae |
| Chlamydia pneumoniae | |
| Allergen | Fungi |
| Tree, weed and grass pollen | |
| Indoor allergens | |
| Occupational | Animal exposures |
| Chemical exposures | |
| Irritants | Airway pollutants |