Kent’s is the best description:
‘Bromium is one of the routine medicines. It is one of the medicines that the neophyte will make use of for every case of diphtheria and croup and laryngitis he comes across; and when it does not work he will “try something else”. All who prescribe on the name use Bromium as one of their routine medicines; but Bromium is so seldom indicated that most homeopaths give it up as a perfectly useless medicine. The reason is that they do not take the symptoms of the case and prescribe in accordance with the individualising method. They do not prescribe for the patient, but for the disease. You may see very few cases of diphtheria calling for Bromium; but when you see a Bromium case you want to know Bromium.
There is one underlying feature of the Bromium conditions, they are found especially in those individuals that are made sick from being heated. If there is a diphtheria epidemic and the mother bundles up her baby until she overheats it, and keeps it in a hot room, and it happens to be a child that is sensitive to being wrapped up, and one whose complaints are worse from being wrapped up, look out. You are going to have a Bromium diphtheria. It is indicated also in complaints that come on in the night after a very hot day in the summer.
Now, this is as near as you can come to being routine in croups and diphtheria. If the mother has the baby out in a dreadfully cold, dry day, and also towards midnight it wakens with spasmodic croups, you know that it is more likely to call for Aconite than any other medicine. But if the mother has had the baby out in a hot day in the summer, and that baby has been overheated, with too much clothing, and it is a plethoric child, and towards midnight you are called up, and the child has a red face, and your examinations reveal a membrane in the throat, we will see as we study the remedy that this may be a Bromium case.