What are the side effects of Aldactone (spironolactone)?

Side Effects of Aldactone (Spironolactone)

Spironolactone commonly causes menstrual irregularities (22%), diuresis (29%), breast tenderness (17%), breast enlargement, fatigue, headache, and dizziness, with hyperkalemia being a potentially serious but rare side effect in young healthy individuals. 1

Common Side Effects

Endocrine and Reproductive Effects

• Menstrual irregularities: Occurs in 22% of patients and may be dose-dependent 1
• Breast-related effects:
  • Breast tenderness (17%) 1
  • Breast enlargement 1
  • Gynecomastia in men (10% compared to placebo) 1
• Sexual dysfunction:
  • Decreased libido 2
  • Erectile dysfunction 2

Gastrointestinal Effects

• Nausea and vomiting 2
• Diarrhea and abdominal cramping 2
• Gastritis (2% of patients) 3
• Gastric bleeding and ulceration 2
• Increased risk of upper gastrointestinal bleeding (approximately twofold, dose-dependent) 4

Neurological Effects

• Headache 1
• Dizziness 1
• Fatigue 1
• Mental confusion 2
• Drowsiness 2
• Lethargy 2
• Ataxia 2

Diuretic Effects

• Diuresis (29% of patients) 1
• Polyuria (1-2%) 1

Serious Side Effects

Electrolyte Abnormalities

• Hyperkalemia:
  • Potentially life-threatening but rare in young healthy individuals 1
  • Occurs in about 5.3% of patients in clinical practice 3
  • Risk factors include renal impairment, diabetes, older age, and concomitant medications affecting potassium levels 1
• Hyponatremia 2
• Hypovolemia 2

Dermatologic Reactions

• Stevens-Johnson Syndrome (SJS) 2
• Toxic epidermal necrolysis (TEN) 2
• Drug rash with eosinophilia and systemic symptoms (DRESS) 2
• Alopecia 2
• Pruritus 2

Hematologic Effects

• Leukopenia (including agranulocytosis) 2
• Thrombocytopenia 2

Hepatic Effects

• Mixed cholestatic/hepatocellular toxicity (rare, with one reported fatality) 2

Renal Effects

• Renal dysfunction including renal failure 2

Special Considerations and Monitoring

Pregnancy and Breastfeeding

• Pregnancy: Should not be used during pregnancy due to potential feminization of male fetuses 1
• Breastfeeding: Limited data suggests low amounts in breast milk with no reported adverse effects in breastfed infants after short-term exposure 2

Potassium Monitoring

• Routine potassium monitoring is not required in young healthy women 1
• Monitoring should be considered in:
  • Older patients 1
  • Patients with hypertension, diabetes, or chronic kidney disease 1
  • Patients taking medications affecting potassium levels (ACE inhibitors, ARBs, NSAIDs, digoxin) 1
  • Recommended schedule: baseline, 1 week, 4 weeks, monthly for first 3 months, then every 3 months 1

Drug Interactions

• Increased risk of hyperkalemia with:
  • ACE inhibitors 1
  • Angiotensin receptor blockers 1
  • NSAIDs 1
  • Potassium supplements 1
  • Other potassium-sparing diuretics 1
  • Potent CYP3A4 inhibitors 1

Metabolic Effects

• Potential transient insulin resistance 5
• Small changes in lipid levels, including decreased HDL cholesterol 5

Practical Management Tips

1. Dosing: Start at lower doses (25 mg daily) and titrate as needed 1
2. Dietary advice: Patients should avoid high-potassium foods, especially low-sodium processed foods and coconut water 1
3. Combined therapy: Consider combined use with oral contraceptives in women to reduce menstrual irregularities 1
4. Discontinuation: Instruct patients to stop spironolactone during episodes of diarrhea or when loop diuretic therapy is interrupted 1
5. Monitoring: If potassium rises above 5.5 mEq/L, reduce dose or discontinue; if above 6.0 mEq/L, stop immediately 1

Despite the black box warning about potential tumorigenicity based on animal studies, several large cohort studies with over 30 million person-years of follow-up have not confirmed such risks in typical clinical practice 1.