Supplements and Naproxen.
Naproxen, sold under the brand name Naprosyn, is a non-steroidal anti-inflammatory drug (NSAID): it inhibits cyclooxygenase enzymes, with documented gastrointestinal and renal long-term risks.
Naproxen is the second most prescribed NSAID in England after ibuprofen. It is the COX-1 and COX-2 inhibitor of choice when a longer plasma half life is useful, with 12-hour dosing rather than 6 to 8. It blocks both cyclooxygenase enzymes, reducing inflammation and pain driven by prostaglandins. But it also reduces the protective gastric and renal prostaglandin signalling that drives the NSAID side effect profile. Sustained NSAID use carries gastric ulceration risk (mitigated when a PPI is co-prescribed), reduced antihypertensive effect of ACE inhibitors and ARBs, additive renal stress in CKD, and additive antiplatelet effect with aspirin. The supplement story splits in two. First, anti-inflammatory supplements (curcumin, boswellia, omega-3 EPA) overlap mechanism with naproxen in the COX pathway. Additive effects exist but rarely clinically problematic at OTC doses. Second, ginkgo, garlic extract, and fish oil at high doses add to bleeding risk when stacked with naproxen, especially around dental work or surgery.
Below are the 7 documented pairs we have explicitly assessed against Naproxen in the Distil database: 7 amber. The pairs cluster around 4 mechanisms: Additive hyperkalaemia (raised potassium), Additive renal stress, 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
Additive hyperkalaemia (raised potassium)
Anti-inflammatory painkillers like naproxen 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 naproxen regularly, mention any potassium supplement to your GP or pharmacist.
Additive renal stress
On its own, creatine is safe for the kidneys in healthy people, and occasional naproxen is fine alongside it. The caution is for taking naproxen often over a long stretch, or if you already have reduced kidney function: naproxen lowers blood flow through the kidneys, and that is the situation where adding creatine's extra workload is worth a doctor's eye. One more practical point: creatine naturally pushes up a blood marker called creatinine, which is the same marker used to check your kidneys, so tell your GP or the lab you take creatine before any kidney blood test on naproxen, or the result can look worse than it really is.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive antiplatelet effect
Bromelain has mild blood-thinning activity that can add to the bleeding risk of anti-inflammatory painkillers like naproxen. The combination is usually fine short term, but stop high-dose bromelain about two weeks before any planned surgery.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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.
Both ginkgo and naproxen 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 naproxen'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 naproxen 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.
Read the full methodologyWant this checked across everything you take?
This page checks the pairs you enter. The personalised Distil report goes further:
- 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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