Asthmatics often get worse from hot baths. It is said that there are several harmful mechanisms involved.
The most studied thing is the action of water vapor.
There are different salts in our cells. These salts retain water. Therefore, the body needs solutions with certain osmotic properties. The same physiological solution, which everyone knows about, contains just enough salt so that water from it is not drawn by other salts in our body.
The water vapor above the hot tub is distilled water. If such water without salts enters the bronchi, then it immediately rushes to the nearest salt.
If there is a cell of our body next to such distilled water, then the water will climb into the cell. From this, the cage will swell and burst at the seams.
The cells don't like this kind of trickery, and so they start to freak out. Some cells contain inflammatory substances inside them. Water stress causes cells to eject inflammatory substances, like a frightened cuttlefish ejects ink. The released inflammatory substances provoke an attack of bronchial asthma.
And even if you plunge into the bath up to your throat, then the water will very noticeably squeeze the chest. This case was measured, and it turned out that immersion in the bathtub reduces the vital capacity of the lungs by 10%, and the reserve expiratory volume decreases by as much as 25%.
The expiratory reserve volume is the amount of air that we can still squeeze out of ourselves after a normal exhalation.
It turns out that the bath squeezes the chest of asthmatics.
It is clear that this will result in less oxygen in the lungs, but it may still be that the very sensation of squeezing asthmatics is considered an exacerbation. Because the feeling of a kind of congestion in the chest is one of the symptoms of bronchial asthma.
I don’t think a bath will be more useful for you than a shower.
