Supplements and Losartan.
Losartan, sold under the brand name Cozaar, is an angiotensin II receptor blocker (ARB): it lowers blood pressure by blocking the angiotensin II receptor directly.
Losartan is an angiotensin II receptor blocker (ARB). It is prescribed as an alternative to ACE inhibitors when the ACE inhibitor cough is not tolerated, or as first line in some hypertension protocols. It blocks the angiotensin II type 1 receptor directly, achieving similar BP reduction without the bradykinin accumulation that drives the cough. Losartan is unusual among ARBs in being a prodrug. It converts to EXP3174 via CYP2C9 and CYP3A4, so the CYP2C9 inhibiting supplements (curcumin at high doses in some studies) carry a theoretical effect on losartan exposure. Renal monitoring is the same as for ACE inhibitors. Annual U&E given the dependence on renin-angiotensin signalling for glomerular filtration pressure. Hyperkalaemia risk rises with potassium-sparing diuretics. Liquorice runs the other way on potassium: at high intake it opposes the BP effect by retaining sodium, driven by glycyrrhizin rather than by aldosterone, and it tends to lower potassium rather than raise it. DGL does not carry the effect. Additive BP lowering from nitrate pathway compounds (beetroot, hibiscus) matters as much as with the ACE inhibitors.
Below are the 11 documented pairs we have explicitly assessed against Losartan in the Distil database: 1 red and 10 amber. The pairs cluster around 3 mechanisms: Additive hyperkalaemia (raised potassium), Additive blood-pressure lowering, and Reduced renal lithium clearance. 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 lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Additive hyperkalaemia (raised potassium)
Red Does Potassium interact with ?
Losartan raises blood potassium by reducing how much the kidneys pass out. A potassium supplement adds more potassium on top. Together they can push potassium high enough to affect the heart rhythm, which can be dangerous. Do not take a potassium supplement alongside losartan unless your GP has specifically advised it and is checking your blood potassium.
Evidence: Supported by human study data.
Additive blood-pressure lowering
Amber Does Beetroot Extract interact with ?
Beetroot lowers blood pressure through the nitric oxide pathway. Losartan lowers it by blocking the angiotensin II receptor. Used together, the combined blood-pressure effect tends to be larger than either alone. Watch for dizziness on standing, especially in the first two weeks. If symptoms appear, tell your GP.
Evidence: Limited human data, based on case reports and a known mechanism.
Amber Does Berberine interact with ?
Berberine can lower blood pressure modestly. Added to losartan the effect may stack. This is usually helpful but can occasionally cause dizziness or a blood pressure that runs lower than intended. Check your blood pressure when you start berberine and tell your GP.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with ?
Garlic supplements have a mild blood-pressure-lowering effect, and losartan lowers blood pressure as well. Together the combined effect tends to be slightly larger. It is usually manageable, but watch for dizziness on standing in the first couple of weeks and mention it to your GP if it happens.
Evidence: Limited human data, based on case reports and a known mechanism.
Amber Does Hibiscus Extract interact with ?
Hibiscus tends to lower blood pressure on its own, and losartan lowers it by blocking the angiotensin receptor. Taken together the blood-pressure effects may stack, so watch for dizziness on standing, especially in the first couple of weeks. If symptoms appear, tell your GP.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does L-Citrulline interact with ?
L-citrulline lowers blood pressure modestly through the nitric oxide pathway, and losartan lowers blood pressure by blocking angiotensin receptors. Used together, the combined blood-pressure effect is mild but real. Watch for dizziness on standing, especially in the first two weeks. If symptoms appear, tell your GP.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Melatonin interact with ?
Taken at night, melatonin can modestly lower blood pressure during sleep. Combined with a blood-pressure medicine like losartan 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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Pine Bark Extract interact with ?
Pine bark extract (pycnogenol) has a mild blood-pressure-lowering effect, and losartan lowers blood pressure as well. Together the combined effect tends to be slightly larger. It is usually manageable, but watch for dizziness on standing in the first couple of weeks and mention it to your GP if it happens.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Spirulina interact with ?
Spirulina has a mild blood-pressure-lowering effect of its own, shown in human trials. Losartan lowers blood pressure by blocking the angiotensin II receptor. Used together, the combined effect tends to be a little larger than the medicine alone. Watch for dizziness on standing in the first couple of weeks, and tell your GP if it happens so your dose can be reviewed.
Evidence: Limited human data, based on case reports and a known mechanism.
Amber Does Taurine interact with ?
Taurine tends to lower blood pressure on its own, and losartan lowers it by blocking the angiotensin receptor. Taken together the blood-pressure effects may stack, so watch for dizziness on standing, especially in the first couple of weeks. The added effect tends to be modest. If symptoms appear, tell your GP.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Reduced renal lithium clearance
Amber Does Lithium Orotate interact with ?
Angiotensin receptor blocker blood pressure tablets such as losartan can reduce how well the kidneys clear lithium, which raises the lithium level in the blood. With prescription lithium this has caused toxicity in reported cases. At the small amount of lithium in a typical lithium orotate supplement (around 5 mg) the effect is expected to be very small; it matters more for higher-strength products (around 20 mg) and for anyone whose kidney function is reduced. If you take one of these blood pressure tablets, check with your pharmacist or GP before using a lithium supplement.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
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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How we grade severity, choose what's in scope, and what we exclude.
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