Side Effects of Spironolactone
Spironolactone commonly causes electrolyte disturbances (particularly hyperkalemia), menstrual irregularities, breast-related effects, and various other side effects that require monitoring but are generally manageable with appropriate dosing and follow-up. 1
Common Side Effects
Endocrine and Reproductive Effects
- Menstrual irregularities: Occurs in 15-30% of women, with risk increasing significantly at higher doses (relative risk of 4.12 for women taking 200mg/day compared to lower doses) 2
- Breast tenderness: 3-5% of patients 2
- Gynecomastia: More common in men, reported in 1.8% of patients in a cardiology practice 3
- Decreased libido and erectile dysfunction 1
- Postmenopausal bleeding 1
Electrolyte and Metabolic Abnormalities
- Hyperkalemia: Most potentially dangerous side effect, occurring in approximately 5.3% of patients 3
- Hyponatremia and hypovolemia 1
- Diuresis: Reported in 29% of patients 2
- Polyuria: 1-2% of patients 2
Gastrointestinal Effects
- Nausea: 2-4% of patients 2
- Gastritis: Reported in 2% of patients in a cardiology practice 3
- Diarrhea, cramping, vomiting, gastric bleeding, and ulceration 1
Neurological Effects
- Dizziness: 3-4% of patients 2
- Lethargy, mental confusion, headache, drowsiness 1
- Impaired neurological function/coma: Particularly in patients with hepatic impairment 1
Dermatologic Effects
- Skin rashes: Including Stevens-Johnson Syndrome, toxic epidermal necrolysis, and DRESS syndrome (rare but serious) 1
- Alopecia and pruritus 1
- "Chloasma": Facial pigmentation (rare) 4
Hematologic Effects
- Leukopenia (including agranulocytosis)
- Thrombocytopenia 1
Risk Factors and Monitoring
High-Risk Populations
- Elderly patients: More likely to have decreased renal function, increasing risk of adverse effects 1
- Patients with renal impairment: At increased risk of hyperkalemia 1
- Patients with hepatic impairment: Risk of sudden fluid/electrolyte alterations that may precipitate hepatic encephalopathy 1
- Patients taking other medications affecting potassium levels 2
Monitoring Recommendations
- Potassium monitoring: Recommended for older patients, those with medical comorbidities, and patients taking medications affecting potassium levels 2
- Renal function: Should be assessed prior to initiating therapy and monitored periodically 1
- Side effect assessment: Regular review during the initial 3 months of treatment is advised as side effects tend to occur early 4
Management Strategies
Dosing Considerations
- Start low: Begin with lower doses (25-50mg daily) to minimize side effects 5
- Cyclic administration: Consider administering 50mg twice daily on days 4-21 of the menstrual cycle to reduce menstrual irregularities 6
- Dose adjustment: If side effects occur, reducing the dose may achieve a compromise between controlling the disease and managing side effects 4
Combination Therapies
- Combined oral contraceptives: Highly effective in regulating menstrual cycles while on spironolactone 2
- Hormonal intrauterine devices: Can help minimize menstrual irregularities 2
Dietary Considerations
- Avoid high-potassium diets to reduce risk of hyperkalemia 2
Special Considerations
Pregnancy and Breastfeeding
- Pregnancy: Spironolactone is pregnancy category C and should not be used during pregnancy due to potential feminization of male fetuses 2
- Breastfeeding: Limited data suggests low amounts of the active metabolite in breast milk, with no adverse effects reported after short-term exposure 1