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[Pharmacology](https://durgical.com/en/pharmacology/) · [Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)

# Fludrocortisone

A corticosteroid used for its strong salt-retaining (mineralocorticoid) effect, to replace aldosterone when the adrenal glands fail.

Updated 2026-11-01

- Class: [Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)
- Receptor: Mineralocorticoid receptor (MR), a nuclear receptor
- ATC code: H02AA02
- WHO Model List of Essential Medicines

◎**Mineralocorticoid receptor (MR), a nuclear receptor**Fludrocortisone

ⓘ The figure shows aldosterone, the natural hormone, in the ligand-binding domain of the human mineralocorticoid receptor; fludrocortisone mimics it in the same pocket.

**Target in 3D:** Mineralocorticoid receptor (MR), a nuclear receptor. PDB structure 2AA2 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/2AA2) · Drag to rotate · pinch to zoom

## Mechanism of action

Fludrocortisone is a 9α-fluorinated cortisol with very strong mineralocorticoid activity. It binds the mineralocorticoid receptor in the distal tubule and collecting duct; the receptor changes gene transcription so that more sodium channels and Na+/K+-ATPase are made. Sodium and water are reabsorbed and potassium and hydrogen ions are lost in the urine. At replacement doses its glucocorticoid effect is usually not important.

- Fludrocortisone binds the mineralocorticoid receptor in the distal nephron
- More sodium channels and Na+/K+-ATPase are made
- Sodium and water are kept; potassium is excreted
- Blood volume and blood pressure rise

## Pharmacokinetics

**Absorption**
Given by mouth as tablets

**Metabolism**
In the liver; enzyme inducers speed its clearance

## Indications

- Primary adrenal insufficiency (Addison disease), together with hydrocortisone [Adrenal insufficiency →](https://durgical.com/en/conditions/adrenal-insufficiency/)
- Salt-losing congenital adrenal hyperplasia

## Adverse effects

### Common

- Fluid retention and oedema
- High blood pressure
- Hypokalaemia
- Headache

### Serious (rare, important)

- Heart failure and cardiac enlargement from salt and water overload
- Hypokalaemic alkalosis
- With prolonged use, the glucocorticoid effects of any corticosteroid

## Contraindications

- Systemic fungal infections
- Hypersensitivity to the product

## Key interactions

**Amphotericin B or potassium-depleting diuretics (thiazides, furosemide)**
Greater hypokalaemia

**Digoxin**
More arrhythmias and digoxin toxicity if potassium falls

**Barbiturates, phenytoin, rifampicin**
Faster clearance and weaker effect

**Oral anticoagulants**
Prothrombin time response may fall; it is monitored

**Oestrogens**
More binding globulin, so the corticosteroid dose may need lowering

## What is monitored

- Blood pressure, including lying and standing
- Serum potassium and sodium
- Weight and oedema

## Administration and safety

- Given by mouth, usually alongside a glucocorticoid in Addison disease
- In stress (surgery, trauma, severe illness) extra corticosteroid cover may be needed, as ordered

## Nursing care

- Check blood pressure and weight; report rapid weight gain or swelling
- Check potassium; watch for muscle weakness or cramps
- Teach the patient to carry identification stating steroid dependence
- Ask about dizziness, severe headache or shortness of breath

## Pregnancy and breastfeeding

Replacement in adrenal insufficiency continues in pregnancy when needed; the dose is reviewed with blood pressure and electrolytes.

## Memory aid

FLUDRO = FLUid DROp-saver: holds salt and water like aldosterone, so watch pressure, oedema and potassium.

## Test yourself

Think of the answer, then tap the question to see it.

## Why does a patient with Addison disease often need fludrocortisone besides hydrocortisone?

Primary adrenal failure loses aldosterone too; fludrocortisone replaces the mineralocorticoid effect that keeps sodium and removes potassium.

## Which electrolyte disturbance does excess fludrocortisone cause?

Hypokalaemia with metabolic alkalosis, plus sodium and water retention with hypertension and oedema.

## Is fludrocortisone needed in secondary (pituitary) adrenal insufficiency?

Usually not: aldosterone is controlled mainly by the renin-angiotensin system, not ACTH, so it is preserved.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/fludrocortisone/)

## Related drugs

- [Hydrocortisone](https://durgical.com/en/pharmacology/hydrocortisone/)

## Related conditions

- [Adrenal insufficiency](https://durgical.com/en/conditions/adrenal-insufficiency/)

[← Back to the class: Corticosteroids (glucocorticoids)](https://durgical.com/en/pharmacology/classes/corticosteroids/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Fludrocortisone Acetate: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682549.html) (MedlinePlus (U.S. National Library of Medicine), 2017); [DailyMed - FLUDROCORTISONE ACETATE tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=eff2eae8-94ce-46ca-a027-6b1d08e7b96b) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=H02AA02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Farmacología básica y clínica (Katzung), 16.ª ed., cap. 39 (McGraw Hill, 2025).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/fludrocortisone/