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 and, relevant for supplements, with liquorice taken in large amounts. 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
Additive hyperkalaemia (raised potassium)
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.
Additive blood-pressure lowering
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.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Reduced renal lithium clearance
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.
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.
How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
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- the same graded, cited interaction check across your whole stack, not just the pairs you thought to type in
- where your current routine may be leaving you short of your goals
- the evidence-backed compounds worth adding, and the ones worth dropping
It's a paid report: £79, or £49 for the first 25 customers. The interactions check is one section of it, and you can read a real one in full before you buy.
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