Garlic Extract and medications.
Garlic Extract is in the Distil supplement database, evidence Grade A. The page below lists every medication we have explicitly assessed it against.
Garlic extract has Grade A evidence for lowering blood pressure, with Grade B support for cholesterol and only Grade C support for immunity. The immune story is worth stating plainly: the Cochrane review of garlic for the common cold could include just one trial and concluded the evidence was insufficient, that trial came from a garlic-promotion body, and a separate aged-garlic study found no difference in how often people caught colds, only in how rough they felt. One small prevention trial and a severity signal may make it worth trying in winter, and that is the most that can honestly be said. The cholesterol side comes with conditions worth knowing: the pooled trials found a reduction of around 10 percent in total and LDL cholesterol, but only in people whose levels were already slightly raised, and only once it had been taken for more than two months. The form matters more than almost anything else here: aged garlic extract, sold as Kyolic, is what the trials used, and raw garlic or ordinary garlic powder is not a fair substitute for the cardiovascular effect. Ried 2016 pooled twenty trials in 970 people and found systolic pressure fell by around 5 mmHg, and by around 9 mmHg in those who were already hypertensive. Typical doses are 600 to 1,200mg of aged extract or an allicin-standardised product. The interaction profile is what to watch here. Its allicin and ajoene give it a mild antiplatelet effect, so it needs monitoring alongside anticoagulants, and high-dose garlic supplements are usually stopped about two weeks before planned surgery. That interval is a cautious operating rule rather than a figure any trial has established, so treat your surgical or dental team's own instruction as the one that governs. It can also lower levels of the HIV drug saquinavir. Choose the aged form, mind the surgery window, and it does real work for blood pressure.
Below are the 27 documented pairs we have explicitly assessed for Garlic Extract: 5 red and 22 amber. The pairs cluster around 4 mechanisms: P-glycoprotein induction (lowers drug levels), Additive blood-pressure lowering, Additive antiplatelet effect, and Additive glucose lowering. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Last reviewed 28 August 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.
P-glycoprotein induction (lowers drug levels)
Additive blood-pressure lowering
Amber Does Garlic Extract interact with Amlodipine?
Garlic supplements mildly lower 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 or ankle swelling in the first couple of weeks, and tell your GP if symptoms appear.
Evidence: Limited human data, from small studies or case reports.
Amber Does Garlic Extract interact with Bisoprolol?
Garlic supplements mildly lower blood pressure, and bisoprolol lowers it too. The combined effect is small but real. Watch for dizziness on standing in the first couple of weeks and tell your GP if it happens.
Evidence: Limited human data, from small studies or case reports.
Amber Does Garlic Extract interact with Clonidine?
Garlic supplements have a mild blood-pressure-lowering effect of their own, and clonidine lowers blood pressure too. Taken together the combined effect tends to be a little larger. It is usually manageable, but watch for dizziness on standing in the first couple of weeks, and tell your GP if it happens.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Guanfacine?
Garlic supplements have a mild blood-pressure-lowering effect of their own, and guanfacine lowers blood pressure too. Taken together the combined effect tends to be a little larger. It is usually manageable, but watch for dizziness on standing in the first couple of weeks, and tell your GP if it happens.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Indapamide?
Garlic supplements have a mild blood-pressure-lowering effect, and indapamide lowers blood pressure as well. The combined effect tends to be slightly larger. 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.
Amber Does Garlic Extract interact with Losartan?
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, from small studies or case reports.
Amber Does Garlic Extract interact with Ramipril?
Garlic supplements have a mild blood-pressure-lowering effect of their own, and ramipril lowers blood pressure too. Taken together the combined effect tends to be a little larger. It is usually manageable, but watch for dizziness on standing in the first couple of weeks, and tell your GP if it happens.
Evidence: Limited human data, from small studies or case reports.
Additive antiplatelet effect
Amber Does Garlic Extract interact with Acenocoumarol?
Garlic supplements can thin the blood by reducing how well platelets clump, which adds to the blood-thinning effect of acenocoumarol and may raise bleeding risk. Culinary amounts of garlic are not the concern; concentrated extracts are. If you take acenocoumarol, discuss garlic supplements with your anticoagulant clinic and watch for easy bruising or bleeding.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Aspirin?
Garlic has mild blood-thinning activity that can add to aspirin's. At culinary doses the combination is usually fine, and high-dose garlic supplements should be stopped at least two weeks before any planned surgery, with your surgical or dental team told you take them.
Evidence: Limited human data, from small studies or case reports.
Amber Does Garlic Extract interact with Clopidogrel?
Garlic has mild blood-thinning activity that can add to clopidogrel's. Stop high-dose garlic supplements at least two weeks before any planned surgery, tell your surgical or dental team you take them, and tell your GP if you take garlic alongside clopidogrel long-term.
Evidence: Limited human data, from small studies or case reports.
Amber Does Garlic Extract interact with Diclofenac sodium?
High-dose garlic extract has its own mild antiplatelet effect on top of diclofenac's. For occasional pain relief at standard doses, this is rarely a problem. For chronic NSAID use or pre-surgery, the combined effect can mean more bleeding and bruising.
Evidence: Limited human data, from small studies or case reports.
Amber Does Garlic Extract interact with Ibuprofen?
High-dose garlic extract has its own mild antiplatelet effect on top of ibuprofen's. For occasional pain relief at standard doses, this is rarely a problem. For chronic NSAID use or pre-surgery, the combined effect can mean more bleeding and bruising. Stop garlic supplements at least two weeks before any planned surgery and tell your surgical or dental team you take them.
Evidence: Limited human data, from small studies or case reports.
Amber Does Garlic Extract interact with Naproxen?
High-dose garlic extract has its own mild antiplatelet effect on top of naproxen's. For occasional pain relief at standard doses, this is rarely a problem. For chronic NSAID use or pre-surgery, the combined effect can mean more bleeding and bruising.
Evidence: Limited human data, from small studies or case reports.
Amber Does Garlic Extract interact with Warfarin sodium?
Garlic at supplement doses has a mild blood-thinning effect of its own. Combined with warfarin, that can shift INR. If you take both, mention the garlic supplement to whoever monitors your INR and do not stop or start without telling them.
Evidence: Supported by human study data.
Additive glucose lowering
Amber Does Garlic Extract interact with Dapagliflozin?
Garlic supplements may lower blood sugar a little on their own. Dapagliflozin also lowers blood sugar but rarely pushes it too low on its own, so the combination is generally manageable. Monitor your glucose when you start a garlic supplement or change the dose.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Empagliflozin?
Garlic supplements may lower blood sugar a little on their own. Empagliflozin also lowers blood sugar but rarely pushes it too low on its own, so the combination is generally manageable. Monitor your glucose when you start a garlic supplement or change the dose.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Gliclazide?
Garlic supplements may lower blood sugar a little on their own. Gliclazide already lowers blood sugar and carries one of the higher risks of pushing it too low among the common diabetes tablets, so taking the two together may add up. If you take both, monitor your blood glucose, especially in the first few weeks, and your doctor may need to adjust the gliclazide dose.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Glimepiride?
Garlic supplements may lower blood sugar a little on their own. Glimepiride already lowers blood sugar and can push it too low, so taking the two together may add up. If you take both, monitor your blood glucose, especially in the first few weeks, and your doctor may need to adjust the glimepiride dose.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Insulin glargine?
Garlic supplements may lower blood sugar a little on their own, on top of the insulin you inject. This may increase the chance of glucose going too low. If you take a garlic supplement with insulin, monitor your blood glucose closely, especially early on, and your doctor may need to reduce your insulin dose.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Metformin?
Garlic supplements may lower blood sugar a little on their own. Metformin also lowers blood sugar, so the two may add up. The combination is generally manageable because metformin on its own rarely causes low blood sugar, but monitor your glucose when you start a garlic supplement or change the dose, and your doctor may adjust the metformin if needed.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Pioglitazone hydrochloride?
Garlic supplements may lower blood sugar a little on their own. Pioglitazone also lowers blood sugar but rarely pushes it too low on its own, so the combination is generally manageable. Monitor your glucose when you start a garlic supplement or change the dose.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with Sitagliptin?
Garlic supplements may lower blood sugar a little on their own. Sitagliptin also lowers blood sugar but rarely pushes it too low on its own, so the combination is generally manageable. Still, monitor your glucose when you start a garlic supplement or change the dose.
Evidence: Limited human data, from small studies or case reports.
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. Use the checker below to surface any medication, 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.
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.
Read the full methodologyA 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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