Corticosteroids, such as dexamethasone and budesonide, can be used to treat croup. People begin to improve a lot within six hours after taking steroids. Steroids work when given by mouth, injection, or inhalation (breathing them in), but taking them by mouth is best. Most of the time, a single dose is enough. Dexamethasone at doses of 0.15, 0.3 and 0.6 mg/kg appear to be all equally good.