Dexamethasone suppression tests are used to assess the status of the hypothalamic-pituitary-adrenal (HPA) axis and for the differential diagnosis of adrenal hyperfunction. The low-dose dexamethasone suppression tests are used to assess nonsuppressible cortisol production by adrenal incidentalomas and to differentiate patients with Cushing's syndrome of any cause from patients who do not have Cushing's syndrome. The high-dose dexamethasone suppression tests help to distinguish patients with Cushing's disease (Cushing's syndrome caused by pituitary hypersecretion of corticotropin [ACTH]) from most patients with the ectopic ACTH syndrome (Cushing's syndrome caused by nonpituitary ACTH-secreting tumors).
Along with its useful effects, dexamethasone can cause unwanted side-effects which your doctor will discuss with you. The benefits of taking an oral steroid usually outweigh the side-effects; however, they can sometimes be troublesome. The table below contains some of the most common ones associated with dexamethasone. The best place to find a full list of the side-effects which can be associated with your medicine, is from the manufacturer's printed information leaflet supplied with the medicine. Alternatively, you can find an example of a manufacturer's information leaflet in the reference section below.
Dexamethasone has also been used during pregnancy as an off-label prenatal treatment for the symptoms of congenital adrenal hyperplasia (CAH) in female fetuses. CAH causes a variety of physical abnormalities, notably ambiguous genitalia in girls. Early prenatal CAH treatment has been shown to reduce some CAH symptoms, but it does not treat the underlying congenital disorder . This use is controversial: it is inadequately studied, only around one in ten of the foetuses of women treated are at risk of the condition, and serious adverse events have been documented.  Experimental use of dexamethasone in pregnancy for foetal CAH treatment was discontinued in Sweden when one in five cases suffered adverse events.