Systemic corticosteroids have the potential to cause severe adverse effects (e.g., gastrointestinal bleeding, sepsis, pneumonia, and adrenal suppression), with systemic adverse effects more common with parenteral or long-acting corticosteroids.

Typically treat for 3 days and then review. Parenteral corticosteroids required for severe and life-threatening exacerbations can be given for up to 10 days with regular review.

And this applies for both Dexamethasone and Prednisolone, however prednisolone is the first choice due to the limited data available for Dexamethasone in asthma.

Ref: GINA 2023, BTS/SIGN 2019