Supplements and Diclofenac sodium.
Diclofenac sodium, sold under the brand names Voltarol, Voltaren, is a non-steroidal anti-inflammatory drug (NSAID): it inhibits cyclooxygenase enzymes, with documented gastrointestinal and renal long-term risks.
Diclofenac sodium is an NSAID, a non-steroidal anti-inflammatory drug. The class inhibits cyclooxygenase enzymes (COX-1 and COX-2 depending on selectivity), reducing pain and inflammation driven by prostaglandins. It also reduces the protective gastric and renal prostaglandin signalling that drives the side effect profile. Use at high doses or sustained over time carries gastric ulceration risk (mitigated when a PPI is given alongside), reduced antihypertensive effect of ACE inhibitors and ARBs, additive renal stress in CKD3+, and additive antiplatelet effect with aspirin or clopidogrel. The supplement surface divides into two patterns. Compounds that target the same pathway (curcumin, boswellia, omega-3 EPA at higher doses) overlap mechanism with NSAIDs in the COX cascade. Additive effects are real but rarely problematic at OTC doses. Ginkgo, garlic extract, and fish oil at high doses add to bleeding risk when stacked with NSAIDs, especially around dental work or surgery.
Below are the 6 documented pairs we have explicitly assessed against Diclofenac sodium in the Distil database: 6 amber. The pairs cluster around 4 mechanisms: Absorption interference, Additive hyperkalaemia (raised potassium), Additive antiplatelet effect, 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
Absorption interference
A small human study found that drinking a hibiscus beverage alongside diclofenac changed how much of the drug appeared in the urine, which suggests hibiscus may slightly affect how diclofenac is handled by the body. The effect is not well characterised and may be minor, but if you take both regularly it is worth separating them by a couple of hours and mentioning it to your GP or pharmacist.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive hyperkalaemia (raised potassium)
Anti-inflammatory painkillers like diclofenac can make the kidneys hold on to a little more potassium. On their own the effect is usually small, but added to a potassium supplement, and especially if your kidneys are not working at full strength or you take a blood-pressure medicine that also raises potassium, it can nudge your potassium higher. If you take diclofenac regularly, mention any potassium supplement to your GP or pharmacist.
Additive antiplatelet effect
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.
Both ginkgo and diclofenac can slow blood clotting. Used together for short periods at standard doses, the combined effect is usually mild. Used at high doses for long periods, the combined effect can mean more bleeding and bruising. Stop ginkgo at least two weeks before any planned surgery.
High-dose omega-3 has a mild antiplatelet effect that adds to diclofenac's. At typical supplement doses and short-course NSAID use, the combined effect is usually mild. At high doses or for chronic NSAID use, the additive bleeding tendency is worth knowing about.
Reduced renal lithium clearance
Anti-inflammatory painkillers such as diclofenac can make the kidneys hold on to lithium, which raises the lithium level in the blood. With prescription lithium this is a recognised caution. 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 regular anti-inflammatories, 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
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