Fludrocortisone, sold under the brand name Florinef, among others, is a corticosteroid used to treat adrenogenital syndrome, postural hypotension, and adrenal insufficiency.

[3] Other serious side effects can include low immune-system function, cataracts, muscle weakness, and mood changes.

The fludrocortisone suppression test is an alternative to the NaCl challenge (which would use normal saline or salt tablets).

[14] Plasma renin, sodium, and potassium are checked through blood tests to verify that the correct dosage is reached.

[medical citation needed] Fludrocortisone, also known as 9α-fluorocortisol (9α-fluorohydrocortisone) or as 9α-fluoro-11β,17α,21-trihydroxypregn-4-ene-3,20-dione, is a synthetic pregnane steroid and a halogenated derivative of cortisol (11β,17α,21-trihydroxypregn-4-ene-3,20-dione).

[2][19] Fludrocortisone is marketed in Austria, Croatia, Denmark, Germany, Luxembourg, Romania, and Spain, whereas fludrocortisone acetate is more widely available throughout the world and is marketed in the United States, Canada, the United Kingdom, various other European countries, Australia, Japan, China, Brazil, and many other countries.