Nausea is an uneasiness of the stomach that often precedes vomiting. Nausea and vomiting are not diseases, but they are symptoms of many conditions. There are numerous cases of nausea and vomiting. Some causes may not require medical treatment, for example, motion sickness, and other causes may require medical treatment by a doctor, for example, heart attack, lung infections, bronchitis, and pneumonia.
Some causes of nausea and vomiting may be life threatening, for example, heart attack, abdominal obstruction, and cancers.
Treatment of nausea and vomiting depends upon the cause.
There is increasing evidence for the use of Steroids for the treatment of the more severe end of the Nausea and Vomiting spectrum, know as Hyperemesis Gravidarum. Steroids have been used for a number of years in pregnancy for conditions such as acute asthma and Crohns disease. There may be a small increased risk of oral clefting associated with the use of corticosteroids and many authorities say that they should not be used to treat nausea and vomiting in pregnancy in the first 12 weeks of pregnancy, however, recent more recent studies are questioning this. There is emerging data on the effectiveness of corticosteroids to treat severe and persistent nausea and vomiting in pregnancy and hyperemesis gravidarum. Corticosteroids need to be given under medical supervision and assessment. They are normally started in hospital Intravenously at a high dose and then tapered off over a number of weeks.
For a minority of patients, perhaps 3-4 %, a serious allergic reaction is possible, which could land a person in the ER or worse! A further percentage have symptoms, such as facial flushing, although of lesser intensity. They want to be on the safe side, and give everyone high amounts of DEX, even though many people would have no problem with less. You are quite right that it also depresses the immune system. For this reason, I requested going on half dose for chemo #1, then, 14 mg for chemo #2, 6 mg for chemo #3, and 4 mg for the fourth session. (These amounts are total dosages, including some pre-tablets during cheno #1 and #2. If anything, each chemo session has resulted in fewer and fewer side effects. (But I have no idea why this could be the case)
As an "older person", I think my immune system needs all the help it can get!