Medication · potassium sparing diuretic

Supplements and Spironolactone.

Every documented pair, every citation. Below: 2 documented pairs grouped by mechanism.

Spironolactone, sold under the brand name Aldactone, is a potassium-sparing diuretic: it blocks aldosterone or epithelial sodium channels, conserving potassium.

Spironolactone is a diuretic that spares potassium. The class includes spironolactone and eplerenone (mineralocorticoid receptor antagonists), and amiloride and triamterene (epithelial sodium channel blockers). UK prescribing centres on spironolactone for heart failure, resistant hypertension, primary aldosteronism, and (outside the licence at low doses) acne. The supplement surface centres on potassium. Anything that adds to potassium load (foods rich in potassium at high intake, salt substitutes containing potassium chloride, magnesium at high doses with associated potassium effects) stacks on top and can drive hyperkalaemia, particularly in patients with reduced renal function. Real liquorice opposes the BP lowering effect by retaining sodium, driven by glycyrrhizin rather than by aldosterone, which reads low. Spironolactone's androgen-blocking activity at higher doses interacts notionally with the same property in herbal supplements (saw palmetto). But the clinical magnitude is small.

Below are the 2 documented pairs we have explicitly assessed against Spironolactone in the Distil database: 1 red and 1 amber. The pairs cluster around 2 mechanisms: Additive hyperkalaemia (raised potassium) and Additive blood-pressure lowering. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.

Documented interactions

Last reviewed 14 June 2026. Each interaction below is assessed against PubMed-indexed evidence.

Additive hyperkalaemia (raised potassium)

Red Does Potassium interact with ?

Spironolactone is a potassium-sparing diuretic, which means it makes the body hold on to potassium. Adding a potassium supplement on top can push potassium to a dangerous level and affect the heart rhythm. This is one of the higher-risk combinations. Do not take potassium with spironolactone unless your specialist has advised it and is monitoring your blood potassium closely.

Evidence: Well established across multiple human studies or interaction references.

PMID 16624686 · PMID 15632880 · PMID 21438068 · BNF: Spironolactone

Additive blood-pressure lowering

Amber Does Melatonin interact with ?

Taken at night, melatonin can modestly lower blood pressure during sleep. Combined with a blood-pressure medicine like spironolactone this may add up to a slightly larger drop than the medicine alone. This is usually mild and often welcome, but if you notice dizziness or lightheadedness, check your blood pressure and mention it to your prescriber.

Evidence: Based on an established mechanism, with no direct study of this exact combination yet.

PMID 14732734 · BNF: Melatonin · BNF: Spironolactone

Reviewer-flagged: awaiting clinical-reviewer sign-off.

What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP or pharmacist, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

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