Asthma is a serious condition, and can be fatal.
What works for one person may not for another.
THUS, each person has to have their own prescribed meds.
I have asthma. Since childhood. Even now currently, there is no one thing that will "cure" it. It is an ongoing condition.
You NEED to know, that in the midst of an asthma attack... or episode, you NEED to use your son's meds or inhalers. Asthma is like suffocating... and if he does not get enough oxygen into his bloodstream it can also strain the heart... and that is how some people die from it. On your own, there is NO way you can monitor his vitals. In this situation, it is critical to use his meds. It has to open up his constricted airways. Immediately.
On a daily basis as well, the inhalers serves as a therapeutic help, for the lungs. It is ongoing. It is "maintenance" for the lungs. And important. It helps to improve the integrity of the lungs and its functioning.
There are many different kinds of inhalers. Fast acting/'rescue' inhalers and daily maintenance inhalers. Often 2 are prescribed for this reason. Working in tandem with each other. Then there are steroidal inhalers... which in a bad asthma episode in VITAL in taking, to reduce lung inflammation and improve breathing levels and oxygen intake.
You cannot just use "natural" remedies willly nilly. It can be dangerous.
Sure, keep the home dust free, use air purifiers etc., and non-toxic household products. But these are not "cures" but rather, reducing the irritants that can make it worse.
Also what can exacerbate asthma is cold weather or stress. For me personally, my asthma gets worse whenever I am sick with even a cold. Therefore, I AVOID sick people as much as possible. Sulphites also makes my asthma worse and preservatives... not all, just some. But that is for MY condition and body. It may not be for your son.
Each case, is different. Therefore, you cannot just do and use what other people do and use.
Also, "deep breathing" exercises can help to strengthen the lungs and its functioning. But it won't "cure" or stop asthma. But it helps. You can look it up online to learn how.
The point is: you NEED to use meds for Asthma. It can be fatal. If you do not give it to him, it can make him worse. Especially if he is in an active asthmatic attack or episode. And it can take time for that episode to diminish.
If you want to know about nutrition for him per asthma/ his allergies, then get referred to a Pediatric Nutritionist per HIS condition. Specifically.
But even with vigilance about it, Asthma is still there and can act up at any time. And you need to monitor it and him.
all the best,