Spironolactone and Drowsiness
Yes, spironolactone can cause drowsiness, though it is not among the most common side effects. 1
Evidence from FDA Drug Labeling
The FDA-approved prescribing information explicitly lists drowsiness as an adverse reaction associated with spironolactone use, categorizing it under "Nervous system/psychiatric" effects alongside lethargy, mental confusion, ataxia, dizziness, and headache. 1
In acute overdosage situations, drowsiness is specifically mentioned as one of the manifestations, along with mental confusion, rash, nausea, vomiting, and dizziness. 1
Clinical Context and Frequency
Drowsiness appears to be an uncommon but recognized side effect in clinical practice:
In cardiovascular practice, a large retrospective study of 762 patients taking spironolactone over 7 years found that only 10.6% experienced any side effects, with the most common being hyperkalemia (5.3%), gynecomastia (1.8%), and gastritis (2%). Drowsiness was not specifically quantified as a major concern in this population. 2
In women treated for hirsutism, drowsiness was not reported among the primary side effects, which were dominated by menstrual irregularities (metrorrhagia in 56% at higher doses). 3
The most frequently reported side effects of spironolactone (occurring in >10% of patients) are headache, diarrhea, fatigue, gynecomastia, decreased libido, and menstrual disruption—not drowsiness. 4
Comparison with Other Medications
When spironolactone is compared to other antihypertensive agents in pediatric guidelines, clonidine is specifically noted to cause sedation, while spironolactone's main warnings focus on hyperkalemia risk, particularly when combined with ACE inhibitors or ARBs. 4 This suggests drowsiness is less prominent with spironolactone than with centrally-acting agents.
Clinical Implications
If a patient reports drowsiness on spironolactone:
Consider dose-dependent effects—lower doses (25-50 mg/day) may minimize this side effect while maintaining efficacy for most indications. 5
Evaluate for other contributing factors including concurrent medications (particularly if combined with sedating agents like benzodiazepines or antipsychotics), electrolyte abnormalities (hyponatremia), or hepatic dysfunction. 1
Monitor for more serious neurological effects such as lethargy or mental confusion, which may indicate electrolyte disturbances or, in patients with liver disease, impending hepatic encephalopathy. 1
The risk of drowsiness should not typically preclude spironolactone use, as it occurs far less frequently than the drug's major side effects (hyperkalemia, gynecomastia, menstrual irregularities, and decreased libido). 6, 1, 2