In practice we use modified forms of these hormones to get fewer side effects. It is the quick-acting hormone from the middle of the adrenal glands near our kidneys. It makes your pulse race, makes your heart thump, and readies your body for emergency action. In asthma, the medicines which resemble adrenaline quickly relieve asthma for a short time. So they are called 'relievers' .
Hydrocortisone comes from the outer part of our adrenal glands, called the 'cortex'.
It is also partly an emergency hormone but it works much more slowly, for much longer, and in a completely different way from adrenaline. Medicines which resemble it act slowly make the lining of air tubes in asthma more normal. So your asthma becomes less bad and you are less likely to get asthma attacks. So these steroid medicines are called 'preventers'. There are other asthma 'preventers', but the steroids are the most powerful.