Supplements and Amlodipine.
Amlodipine, sold under the brand names Istin, Norvasc, is a calcium channel blocker: it relaxes vascular smooth muscle and reduces afterload.
Amlodipine is a long-acting calcium channel blocker in the dihydropyridine class. Prescribing is mostly hypertension and stable angina. It blocks L-type calcium channels in arterial smooth muscle, dropping peripheral resistance and afterload. The side effect most often reported is ankle oedema, from preferential dilation of arterioles over venules. It scales with dose. It is not a sign of heart or kidney trouble. Amlodipine is metabolised by CYP3A4, but the therapeutic window is wide enough that 3A4 interactions rarely matter at standard doses. Where supplements meet amlodipine, the main signal is additive blood pressure lowering. Beetroot extract, hibiscus, garlic, and the nitrate pathway compounds can stack on top. Sometimes useful. Sometimes pushing systolic too low. The combination flagged in the BNF is grapefruit juice, since 3A4 inhibition can push amlodipine plasma levels up by 20 to 30 percent. Anyone titrating an antihypertensive supplement stack alongside amlodipine should keep a home BP log rather than assume the baseline holds.
Below are the 11 documented pairs we have explicitly assessed against Amlodipine in the Distil database: 10 caution and 1 good to know. The pairs cluster around 3 mechanisms: Additive blood-pressure lowering, Reduced blood-pressure-medicine effect, and CYP3A4 inhibition. 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 13 October 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 blood-pressure lowering
Caution Does Beetroot Extract interact with Amlodipine?
Beetroot lowers blood pressure through the nitric oxide pathway. Amlodipine lowers blood pressure through calcium-channel blockade in vascular smooth muscle. Both mechanisms cause vasodilation, so the combined effect tends to be larger than either alone. Watch for dizziness on standing or ankle swelling, especially in the first two weeks. If symptoms appear, tell your GP.
Evidence: Limited human data, from small studies or case reports.
Caution Does Berberine interact with Amlodipine?
Berberine may lower blood pressure a little. Added to amlodipine the effect may stack, which is sometimes helpful but may occasionally cause dizziness or a blood pressure that runs lower than your GP intended. Check your blood pressure when you start berberine and tell your GP.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Garlic Extract interact with Amlodipine?
Garlic supplements may lower blood pressure a little, mostly when it is above target, and amlodipine lowers it too, so together they may bring it down a bit further. If you feel dizzy or light-headed, especially when you stand up, check your blood pressure and tell your GP. Garlic's effect tends to build over several weeks, so keep an eye on your readings for the first three months or so.
Evidence: Limited human data, from small studies or case reports.
Caution Does Hibiscus Extract interact with Amlodipine?
Hibiscus tends to lower blood pressure on its own, and amlodipine lowers it by relaxing blood vessels. 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, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does L-Citrulline interact with Amlodipine?
L-citrulline lowers blood pressure modestly through the nitric oxide pathway, and amlodipine lowers blood pressure by relaxing blood vessels through calcium-channel blockade. 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, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Pine Bark Extract interact with Amlodipine?
Pine bark extract (pycnogenol) mildly lowers blood pressure, and amlodipine lowers it too. The combined effect tends to be a little larger than either alone. It is usually manageable, but watch for dizziness on standing in the first couple of weeks and tell your GP if symptoms appear.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Caution Does Spirulina interact with Amlodipine?
Spirulina has a mild blood-pressure-lowering effect of its own, shown in human trials. Amlodipine lowers blood pressure through calcium-channel blockade. 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, from small studies or case reports.
Caution Does Taurine interact with Amlodipine?
Taurine tends to lower blood pressure on its own, and amlodipine lowers it by relaxing blood vessels. Taken together the blood-pressure effects may stack, so watch for dizziness on standing, especially in the first couple of weeks. Taurine's own effect on blood pressure is small. If symptoms appear, tell your GP.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Good to know Does L-Theanine interact with Amlodipine?
In one small study, L-theanine took the edge off a stress-driven rise in blood pressure in some people, but it did not lower resting blood pressure the way a blood-pressure medicine does. At normal supplement doses it is not expected to push your blood pressure too low when taken with amlodipine. If you monitor at home and see readings lower than usual, mention it to your GP.
Evidence: Limited human data, from small studies or case reports.
Reduced blood-pressure-medicine effect
Caution Does Melatonin interact with Amlodipine?
Melatonin has been shown to raise blood pressure and heart rate in people taking the related blood-pressure drug nifedipine, working against it. Amlodipine is in the same drug family, so the same effect may apply. If you take amlodipine, it is worth discussing melatonin with your prescriber and monitoring your blood pressure rather than starting it on your own.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
CYP3A4 inhibition
Caution Does Bergamot Extract (BPF / Bergavit40) interact with Amlodipine?
Bergamot is a citrus fruit related to grapefruit and contains bergamottin, one of the compounds behind grapefruit's effect on medicines, so it may raise amlodipine blood levels a little. Amlodipine is among the calcium-channel blockers least affected by grapefruit, but flag bergamot to your GP before combining, particularly if your blood pressure is already well controlled.
Evidence: Limited human data, from small studies or case reports.
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 the checker decides
Every result has a source
Each pair we have assessed is cited to a published study (PMID) or the British National Formulary, so you can read the source yourself.
Four kinds of answer
Severe, caution, no known interaction, and not yet assessed. A pair we have not assessed is never shown as clear.
- Severe
- Caution
- No known interaction
- Not yet assessed
Nothing in our data is not a clearance
When nothing in our data records a problem with a pair, the result says no known interaction at typical doses, which is not a clearance: your pharmacist or GP can check the pair against your full medical history.
A full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
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