None. Croup is one of those things that can turn nasty without warning. The steriod you need for croup in Prednisolone (sp) or Predimix as it's commonly known as. It's taken straight mixed up with juice or something as it has a horrible taste and not through a ventilator. You would also need to know the measurement to give her as being taken straight, they are very cautious with weight to dose ratio.
If the cough is seal sounding already, that is a pretty good indicator that she needs to see a GP or if you have them over there, a home visiting GP if you get stuck in the night.