Does spironolactone increase intracranial pressure?

October 8, 2025 •

4 min read

While often associated with fluid reduction, spironolactone has a more complex relationship with brain pressure than is widely known. It is sometimes used to lower intracranial pressure (ICP) in conditions like idiopathic intracranial hypertension (IIH), yet a rare case report documented that spironolactone increased intracranial pressure in a susceptible patient.

Quick Summary

Spironolactone's effects on intracranial pressure are complex; while it can marginally reduce ICP in some cases, rare instances of increased pressure have been documented in predisposed individuals, necessitating careful clinical consideration.

Key Points

Standard Use: Spironolactone is a diuretic that typically reduces fluid volume and is used to help lower ICP in idiopathic intracranial hypertension (IIH).
Rare Adverse Effect: A case report documented a patient with a history of IIH who experienced a significant increase in intracranial pressure after starting spironolactone.
Risk Factors: Individuals with a history of IIH, obesity, or other predisposing conditions may be at a heightened, though rare, risk of this adverse reaction.
Possible Mechanisms: The exact cause of the adverse ICP increase is unknown, but researchers speculate it may involve interactions with central neurotransmitter systems.
Symptom Resolution: In the documented case, the patient's symptoms of increased ICP, including headache and blurred vision, resolved after the spironolactone was discontinued.
Clinical Precaution: Clinicians should exercise caution and closely monitor patients with a history of IIH when prescribing spironolactone, and patients should be aware of key symptoms.
Therapeutic vs. Adverse: The medication exhibits a dual nature regarding ICP, showcasing both a therapeutic lowering effect and, in rare instances, a potential to increase it, highlighting complex pharmacological interactions.

The Dual Role of Spironolactone in Intracranial Pressure

Spironolactone is a well-known medication used for a variety of conditions, primarily as a potassium-sparing diuretic. It is most commonly prescribed for heart failure, hypertension, and edema. However, its use in managing intracranial pressure (ICP) presents a seemingly contradictory picture based on clinical findings.

How Spironolactone Can Lower ICP

Spironolactone's primary mechanism is its role as an aldosterone antagonist. Aldosterone is a hormone that regulates the balance of sodium and water in the body. By blocking aldosterone, spironolactone increases the excretion of sodium and water while retaining potassium. This fluid-reducing effect is the foundation of its use in lowering fluid pressure throughout the body. In a clinical setting, this is the expected action. Recent research has investigated this effect specifically within the context of idiopathic intracranial hypertension (IIH), a condition characterized by high pressure inside the skull with no apparent cause.

In a 2025 study published in the NIH database, researchers conducted a cross-over trial comparing several diuretics, including spironolactone, in patients with active IIH.
The results showed that spironolactone marginally but significantly reduced ICP over a two-week period.
This reduction was similar to the effects seen with other diuretics like furosemide, though the authors noted the clinical significance of the modest change was unknown.
Spironolactone is also sometimes used as a second-line treatment for IIH, further suggesting its therapeutic potential to lower ICP.

The Rare Case of Increased ICP

Despite the evidence suggesting spironolactone can lower ICP, a rare and important case report from 2018 highlights the potential for the opposite effect. This case involved a 39-year-old woman with a history of inactive IIH who was prescribed spironolactone for androgenetic alopecia (hair loss). After starting the medication, she experienced a significant increase in her ICP, accompanied by classic symptoms such as severe headache, blurred vision, and papilledema (optic nerve swelling).

The patient had a long-standing history of IIH that had been inactive for many years.
Her symptoms progressively worsened after the spironolactone dosage was increased.
The recurrence of IIH was suspected, and her symptoms resolved completely after the medication was discontinued.
This case serves as a critical reminder that patient-specific factors can influence drug response in unexpected ways, especially for those with a pre-existing predisposition to certain conditions.

Possible Mechanisms for the Conflicting Effects

The contrasting effects of spironolactone on ICP—therapeutic reduction versus adverse increase—stem from its complex pharmacology and the varied pathophysiological processes in different patients. The primary diuretic action of spironolactone is straightforward, reducing fluid volume and thereby pressure. However, the mechanism behind the adverse ICP increase remains largely unknown but could involve more complex neurological pathways.

In the reported case, researchers speculated that spironolactone might affect central and peripheral neurotransmitter systems, specifically by deregulating dopaminergic and gamma-aminobutyric acid (GABA) activity. This could theoretically lead to an increase in cerebrospinal fluid (CSF) production or altered cerebral blood flow in a patient already susceptible to high ICP. Other factors, like obesity and polycystic ovarian syndrome (PCOS), which were present in the reported patient, are also known to be risk factors for IIH and could have interacted with the medication.

Comparison of Spironolactone's Effects on ICP


Aspect	Therapeutic ICP-Lowering Effect	Adverse ICP-Increasing Effect
Patient Population	Individuals with active IIH.	Rare cases, potentially in individuals with a history of IIH or other risk factors.
Mechanism of Action	Diuretic effect via aldosterone antagonism, leading to reduced fluid volume.	Unknown, speculated to involve central neurotransmitter deregulation.
Onset of Action	Typically observed within the timeframe of a clinical study, potentially gradual.	In the documented case, symptoms worsened over months after a dose increase.
Outcome	Marginal but measurable ICP reduction in controlled studies.	Symptomatic recurrence of intracranial hypertension, resolving upon discontinuation.
Clinical Context	Used as a second-line treatment for IIH.	A rare, paradoxical reaction requiring immediate cessation of the medication.

Important Considerations for Prescribing Spironolactone

This rare adverse event underscores the importance of a thorough patient history and careful monitoring, particularly when prescribing spironolactone to individuals with a known or suspected history of IIH or other risk factors. Clinicians should also be aware of the less common neurological side effects, such as headaches, which could mask early signs of rising ICP.

Pre-existing Conditions: A history of IIH, even if inactive, should be considered a significant risk factor.
Symptom Monitoring: Patients should be educated to recognize and report signs of increased ICP, such as worsening headaches, vision changes, and tinnitus.
Treatment Adherence: Non-adherence to monitoring protocols can delay recognition of an adverse reaction, as was suggested in the case study.
Differential Diagnosis: When new-onset or worsening neurological symptoms occur during spironolactone therapy, increased ICP should be considered in the differential diagnosis.

Conclusion

In conclusion, while spironolactone's primary function as a diuretic would suggest an ICP-lowering effect, and clinical studies have shown it can reduce ICP in IIH patients, the medication has also been linked to rare cases of increased intracranial pressure. This paradoxical effect highlights the need for clinicians to maintain vigilance, especially when treating patients with a history of IIH or other predisposing conditions. The underlying mechanism for this adverse reaction is not fully understood, but its documented occurrence emphasizes the importance of patient education and careful clinical monitoring. The case report serves as a valuable clinical lesson, reminding practitioners that even widely-used and well-understood medications can produce unexpected and serious side effects in specific patient populations.

Frequently Asked Questions

Yes, spironolactone is sometimes used as a second-line treatment for IIH due to its diuretic properties, which can help reduce fluid volume and potentially lower intracranial pressure.

An increase in intracranial pressure from spironolactone is considered a very rare adverse event. It has been primarily documented in specific case reports rather than being a widespread side effect.

Patients with a history of IIH should watch for symptoms such as worsening headaches, blurred vision, pulsating tinnitus, and visual obscurations, and report them to their doctor immediately.

Spironolactone works by blocking aldosterone receptors in the kidneys, leading to increased excretion of sodium and water. This diuretic action reduces overall fluid volume in the body.

No, if a patient develops symptoms suggestive of increased intracranial pressure while on spironolactone, the medication should typically be discontinued under medical supervision, as observed in the case report where symptoms resolved upon stopping the drug.

Yes, individuals with pre-existing conditions like idiopathic intracranial hypertension, obesity, and polycystic ovarian syndrome may be more susceptible to this rare adverse reaction.

While the connection is speculative and not fully understood, some researchers suggest that spironolactone may affect central neurotransmitter systems (such as dopaminergic and GABA activity), which could potentially contribute to an increase in intracranial pressure in susceptible individuals.