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Mineralocorticoid Pregnancy: Compatible — continue mineralocorticoid replacement through pregnancy; dose may need increasing in third trimester

Fludrocortisone

Brand names: Florinef

Adult dose

Dose: Addison's disease: 50–300 mcg OD. Postural hypotension/autonomic failure: 100–200 mcg OD (specialist use).
Route: Oral
Frequency: Once daily (in the morning)
Max: 300 mcg OD
Primary mineralocorticoid replacement in adrenal insufficiency (used with hydrocortisone). Adjust dose based on sodium, potassium, BP, and postural symptoms.

Paediatric dose

Route: Oral
Frequency: OD
Max: Infants with congenital adrenal hyperplasia: 50–250 mcg OD (higher requirements due to salt-wasting)
Concentration: 100 mcg tablet mg/m²/ml
Infants with CAH salt-wasting: often need 100–250 mcg/day initially. Also give salt supplements 1–3 g/day NaCl in infants.

Dose adjustments

Renal

Caution — sodium and water retention in renal impairment

Hepatic

No specific adjustment; caution in severe hepatic impairment

Clinical pearls

  • Adequate fludrocortisone replacement often overlooked — patients may have chronic fatigue, postural hypotension, salt craving from underreplacement
  • Dose monitoring: check lying and standing BP, weight, serum Na+/K+, and renin levels (target renin upper end of normal range)
  • Sick day rules apply — double hydrocortisone but NOT fludrocortisone dose during illness/surgery
  • Infants with CAH have the highest mineralocorticoid requirements per kg — essential for salt-wasting crisis prevention

Contraindications

  • Congestive heart failure (caution — fluid retention)
  • Severe hypertension
  • Uncontrolled infection

Side effects

  • Hypertension
  • Oedema/sodium retention
  • Hypokalaemia
  • Headache
  • Weakness
  • Cushing-like features (excess dose)

Interactions

  • NSAIDs — increased sodium retention and fluid overload
  • Potassium-lowering drugs (diuretics) — additive hypokalaemia
  • Digoxin — hypokalaemia increases toxicity risk

Monitoring

  • Serum electrolytes (Na+, K+)
  • Blood pressure (lying and standing)
  • Weight (oedema)
  • Plasma renin activity (target upper normal for dose adjustment)
  • Signs of adrenal crisis

Reference: BNFc; BNF; NICE Addison's disease guidance; Society for Endocrinology Addison's guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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