Most Spironolactone side effects are mild, often improve over the first few weeks, and respond to dose adjustments when needed.
Common side effects:
- Breast tenderness or enlargement one of the most commonly reported effects. Usually improves over time but can persist.
- Mild headaches particularly in the first weeks.
- Fatigue or low energy.
- Irritability or mood changes.
- Menstrual changes spotting, irregular periods, heavier or lighter periods than usual. Combined hormonal birth control often smooths these out (see "Can I take birth control pills and Spironolactone at the same time?").
- Increased urination Spironolactone has a mild diuretic effect, so you may notice you need to use the restroom more often.
- GI upset mild nausea, occasional discomfort.
- Decreased libido.
- Dizziness particularly when standing up quickly, due to the diuretic effect on fluid balance.
Less common side effects:
- Muscle cramps, particularly in the legs.
- Dry skin or dry lips.
Important contraindications and risks:
- Spironolactone is not safe during pregnancy. See Q2 above and the dedicated answer in the Reduce Acne section.
- Elevated potassium levels (hyperkalemia) are a known but uncommon risk. Spironolactone affects how your kidneys handle potassium, and in some women — particularly with kidney issues or certain medication combinations — potassium can rise to concerning levels. Your clinician may recommend periodic monitoring.
- Interactions with potassium supplements, ACE inhibitors, or NSAIDs can increase the potassium risk. Always tell your clinician about all medications and supplements you're taking.
What to do:
- Most side effects improve within the first 4 to 8 weeks. Push through the adjustment window if you can.
- Stay hydrated. The mild diuretic effect can dehydrate you faster than usual.
- Limit high-potassium supplements (potassium chloride, salt substitutes containing potassium) unless your clinician specifically recommends them.
- Message your clinician if side effects are bothersome, persistent, or affecting daily life.
- Seek immediate care if you experience irregular heartbeat, severe muscle weakness, significant fatigue with confusion, or signs of an allergic reaction.