Fludrocortisone: What It Is, How It Works, and What You Need to Know

When your body doesn’t make enough natural steroids, fludrocortisone, a synthetic mineralocorticoid used to replace aldosterone and help regulate salt and water balance. It's also known as Florinef, and it’s one of the few drugs specifically designed to help your kidneys hold onto sodium instead of flushing it out. Unlike prednisone or hydrocortisone, which mainly handle inflammation and immune response, fludrocortisone works on your blood pressure and electrolytes. It’s not a painkiller or a mood stabilizer—it’s a precision tool for when your adrenal glands can’t keep your body’s salt and fluid levels in check.

This is why it’s often prescribed for adrenal insufficiency, a condition where the adrenal glands don’t produce enough cortisol and aldosterone, like in Addison’s disease. People with this condition can feel dizzy, weak, and faint when standing up because their blood pressure drops too low. Fludrocortisone helps by making the kidneys reabsorb sodium, which pulls water with it and increases blood volume. That’s how it lifts blood pressure without being a stimulant. It’s also used in some cases of orthostatic hypotension, where standing up causes a sudden drop in pressure. You don’t take it to feel more energetic—you take it so you don’t pass out when you stand up.

Fludrocortisone doesn’t work alone. It’s usually paired with hydrocortisone, a corticosteroid that replaces the cortisol your body is missing. One handles salt and fluid, the other handles stress response, metabolism, and immune function. Missing one can cause serious problems—even if you feel fine, skipping fludrocortisone can lead to dangerous drops in sodium and blood pressure. That’s why doctors monitor your sodium levels, weight, and blood pressure closely when you start it. Too much can cause swelling, high blood pressure, or low potassium. Too little and you risk dehydration or fainting.

You’ll find posts here that dig into how fludrocortisone fits into broader medication management—like how it interacts with other drugs, why some people need it for years, and how it compares to alternatives. You’ll also see how it’s used in real-world settings, from managing chronic conditions to handling emergencies. These aren’t theoretical discussions—they’re based on what pharmacists, doctors, and patients actually deal with every day. Whether you’re just starting fludrocortisone or have been on it for years, the information below will help you understand why it’s prescribed, what to watch for, and how to make sure it’s working the way it should.