Oh, sorry, Emkana, only just seen this, and sorry DS is still unwell. It is completely crap when they're struggling to breathe, isn't it?
DS2 is still using 3 sorts of preventer every day, though I'm not sure he needs them all now. I don't know whether they are all suitable for babies.
He takes Flixotide 1 puff twice daily (fluticasone) which is an inhaler steroid, and a stronger one than the budesonide (Pulmicort) they usually start with. He also takes a Singulair tablet once daily(montelukast, which is a leukotriene receptor agonist, and I believe acts on only one of the asthma pathways, so isn't as effective as a higher dose of steroid). Finally, he takes Serevent 1 puff twice daily(salmeterol) which is a long-acting beta-agonist, which is another less effective preventer, but designed to minimise the steroid dose. When he was younger, he used to take bambuterol paediatric syrup, another long-acting beta-agonist, but that's not available in the UK.
They can take higher doses of the Flixotide if they need to, but the idea of the add-on medicines is to reduce the steroid intake.
Hope some of this is useful, but I'm sure your chest specialist will know all the up-to-date stuff for babies! When we moved to our current GP's practice, to be honest, I just turned up and said "This is what he's been having. What do you think?" and they said "OK. We'll carry on giving it".