Pine Bark Extract and medications.
Pine Bark Extract is in the Distil supplement database, evidence Grade B. The page below lists every medication we have explicitly assessed it against.
Pine bark extract, sold as Pycnogenol, is a procyanidin-rich extract taken at 100 to 200mg a day. It is marketed for a long list of things, and our reading is that the list is much shorter than the marketing suggests. Two uses hold up at Grade B, both from the same 2025 meta-analysis of 27 randomised trials in 1,685 people: blood pressure and lipids, where it may lower systolic and diastolic pressure by around 2 to 3 mmHg and LDL modestly, and glycaemic control, where fasting glucose, HbA1c and body weight all fell. Those are real but small effects, and the authors themselves call for larger and longer trials. We do not offer it for cognition, joint or bone health, skin, or ADHD. A Cochrane review of 27 trials across ten conditions rated every single outcome very low certainty and concluded that no definitive answers are possible; its only cognitive result was null, it declined to pool the osteoarthritis trials, and it found no skin trial at all to include. The ADHD evidence is one four-week study in children at a weight-based dose, which is neither the group nor the dose an adult would be taking. Erectile function is deliberately not on the list either: the trial usually cited gave every participant L-arginine throughout and added pine bark partway, with no placebo group and no pine-bark-alone group, so its result cannot be attributed to pine bark. The interaction angle to watch is a mild antiplatelet effect, in the same low bracket as curcumin and garlic, and in one study a single 200mg dose was still reducing smoking-induced platelet clumping more than six days later, so people on anticoagulants should be aware, and it can modulate immune function, which matters for anyone on immunosuppressants. It is generally very safe, with occasional headache or mild stomach upset. A reasonable option if your interest is blood pressure or blood sugar, and not one we would reach for otherwise.
Below are the 15 documented pairs we have explicitly assessed for Pine Bark Extract: 15 amber. The pairs cluster around 4 mechanisms: Additive blood-pressure lowering, Additive anticoagulation, 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 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 blood-pressure lowering
Amber 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.
Amber Does Pine Bark Extract interact with Bisoprolol?
Pine bark extract (pycnogenol) mildly lowers 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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Pine Bark Extract interact with Indapamide?
Pine bark extract (pycnogenol) has 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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Pine Bark Extract interact with Losartan?
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, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Pine Bark Extract interact with Ramipril?
Pine bark extract (pycnogenol) has a mild blood-pressure-lowering effect of its 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.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive anticoagulation
Amber Does Pine Bark Extract interact with Acenocoumarol?
Pine bark extract (pycnogenol) has a mild blood-thinning effect of its own, shown in people as reduced platelet stickiness, mainly in smokers. It has not been studied alongside acenocoumarol, so the size of any combined effect is unknown. If you take acenocoumarol, tell your anticoagulation clinic before starting pine bark extract and ask for an INR check a couple of weeks in.
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.
Amber Does Pine Bark Extract interact with Warfarin sodium?
Pine bark extract (pycnogenol) has a mild blood-thinning effect of its own, shown in people as reduced platelet stickiness, but only in smokers: in the same study it made no measurable difference to non-smokers. It has not been studied alongside warfarin, so the size of any combined effect is unknown. If you take warfarin, tell your anticoagulation clinic before starting pine bark extract and ask for an INR check a couple of weeks in.
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.
Additive antiplatelet effect
Amber Does Pine Bark Extract interact with Aspirin?
Pine bark extract (pycnogenol) has a mild blood-thinning effect of its own, most clearly shown in smokers, that can add to aspirin's. For most people the combined effect is no more than a small extra tendency to bruise or bleed, and it matters most before surgery. Stop high-dose pine bark extract at least two weeks before any planned procedure and tell your GP if you notice easy bruising.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Pine Bark Extract interact with Clopidogrel?
Pine bark extract (pycnogenol) has a mild blood-thinning effect of its own, most clearly shown in smokers, that can add to clopidogrel's. For most people the combined effect is no more than a small extra tendency to bruise or bleed. Stop high-dose pine bark extract at least two weeks before any planned surgery and tell your GP if you take the two together long-term or notice easy bruising.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Pine Bark Extract interact with Ticagrelor?
Pine bark extract (pycnogenol) has a mild blood-thinning effect of its own, most clearly shown in smokers, that can add to ticagrelor's. The combined effect can mean more bruising or bleeding. Stop high-dose pine bark extract at least two weeks before any planned surgery and tell your GP if you take both together, especially if ticagrelor is combined with aspirin.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive glucose lowering
Amber Does Pine Bark Extract interact with Dapagliflozin?
Pine bark extract (pycnogenol) may lower blood sugar a little on its 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 pine bark extract or change the dose.
Evidence: Limited human data, from small studies or case reports.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Pine Bark Extract interact with Gliclazide?
Pine bark extract (pycnogenol) may lower blood sugar a little on its 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 Pine Bark Extract interact with Insulin glargine?
Pine bark extract (pycnogenol) may lower blood sugar a little on its own, on top of the insulin you inject. This may increase the chance of glucose going too low. If you take pine bark extract 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 Pine Bark Extract interact with Metformin?
Pine bark extract (pycnogenol) may lower blood sugar a little on its 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 pine bark extract 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 Pine Bark Extract interact with Sitagliptin?
Pine bark extract (pycnogenol) may lower blood sugar a little on its 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 pine bark extract 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.
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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
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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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