If you can control it or avoid the trigger, that will be OK. But I think it's temporary. Sometimes it's not just occasional asthma attack due to allergic reaction, you might have other breathing problems which affects you daily.
Since those athletes can't possibly use steroid-based drugs to breathe well day in day out, I guess vigorous physical exercise and some breathing technique/devices can help. Novak's sleeping pod?
As for Djokovic and Lisicki, they aim for gluten-free diet which had improved Djokovic's performance. If it eliminates the allergy, then it's significant improvement.