Fludrocortisone

Key facts

• Fludrocortisone replaces the hormone aldosterone, which the adrenal glands normally make to help the kidneys hold onto sodium and water and release potassium.
• It is taken daily, usually as a single tablet, often alongside a glucocorticoid such as hydrocortisone in Addison's disease.
• Never stop fludrocortisone suddenly and never skip doses during illness, injury, vomiting or surgery. Your body may need a higher dose at these times; stopping abruptly can trigger a life-threatening adrenal (Addisonian) crisis, with severe low blood pressure, vomiting and collapse.
• Seek urgent care for severe dizziness, fainting, persistent vomiting, or rapid, dramatic weight gain with swelling.

What fludrocortisone treats

Fludrocortisone treats Addison's disease and other forms of primary adrenal insufficiency, where the adrenal glands do not make enough aldosterone. It also treats salt-wasting forms of congenital adrenal hyperplasia and some cases of orthostatic (postural) hypotension, where blood pressure falls sharply on standing.

How fludrocortisone works

Aldosterone normally tells the kidneys to reabsorb sodium and water while releasing potassium, which keeps blood volume and blood pressure stable. Fludrocortisone acts on the same kidney receptors as aldosterone. By replacing what the adrenal glands are missing, it restores normal salt and fluid balance and raises blood pressure.

Before you take it

• Tell your prescriber about high blood pressure, heart failure, kidney disease, or a history of low potassium: fludrocortisone can raise blood pressure and cause fluid retention.
• Carry a steroid alert card or medical ID if you take it for adrenal insufficiency, and make sure family members know the sick-day rules for raising your dose.
• NSAIDs (such as ibuprofen), some diuretics and certain other medicines can change how fludrocortisone works or affect your potassium level; tell your prescriber about everything you take.

Side effects

Common effects include mild headache, swelling in the ankles or feet, and nausea, all related to the fluid retention the drug is designed to cause.

Stop and seek urgent medical care for any of these:

• Sudden or severe swelling, rapid weight gain, or shortness of breath.
• Very high blood pressure, chest pain, or a pounding or irregular heartbeat.
• Signs of an adrenal crisis: severe weakness, vomiting, very low blood pressure, or fainting, especially during illness or after missed doses.
• Muscle cramps or weakness, which can signal a low potassium level.

Safety essentials

• Never stop this medicine abruptly if you have adrenal insufficiency. Doses usually need to increase during fever, infection, vomiting, injury or surgery; agree a sick-day plan with your prescriber in advance.
• Your prescriber will check blood pressure, weight, and potassium levels regularly, since fludrocortisone works by holding onto sodium and fluid while releasing potassium.
• Report swelling, rapid weight gain or breathlessness promptly. At high doses fludrocortisone can strain the heart, especially in people with existing heart disease.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.