A lot of people have found fish oil capsules to greatly help their asthma.
And magnesium is one of several vitamins and minerals that are not absorbed when you have gluten problems.
Magnesium is used in emergency medicine for asthma attacks. And there are several articles on google about magnesium helping people with asthma.
My brother had to stop eating gluten (which is in wheat, barley, rye and oats). One of the nice things about that was 95% relief from his asthma. He says milk products were the last 5%. I'm just letting you know that for some people, food can be the culprit. His oxygen level, before going gluten free, would never get higher than 93%. He was on many medications at the time, and they weren't helping. Now he feels like a new person! Maybe you would like to give the diet a try. Let me know if you need help with the diet. Hope this helps!
There is no cure for asthma it can only be controlled with medications. It's just a matter of finding what medications works best for you.