Cognitive Supplements to Stop Before Surgery

The standing editorial rule in the interaction literature is blunt: stop botanical supplements at least two weeks before surgery, and clear everything else with the person doing the operating. Ginkgo biloba is the one with named case reports behind it — subdural hematoma, hyphema and intracerebral bleeding — and the standard advice is to stop it two weeks out. High-dose omega-3, curcumin, resveratrol, saffron, vitamin E, phosphatidylserine and lion’s mane all sit in the same additive-bleeding bucket at varying strengths of evidence, from documented to purely theoretical. Two others run the opposite way and matter just as much: Panax ginseng and CoQ10 can lower INR, and acetyl-L-carnitine has case reports of raising it.

Written by the Fog & Clarity editorial team · Published 30 July 2026 · Last updated 30 July 2026

⚠️ Talk to your prescriber first

Tell your surgeon, your anesthetist and your prescriber everything you take — including things you do not think of as medicine: capsules, powders, gummies, teas, mushroom coffees. Bring the actual bottles to pre-op if you can. And do not stop a prescribed anticoagulant or any other prescription on your own because of something you read here; stopping those is a clinical decision with its own risks.

The mechanism

Most of the concern is platelet function. Several of the botanicals sold for memory and focus have antiplatelet activity — ginkgo’s ginkgolides inhibit platelet-activating factor; curcumin and resveratrol inhibit platelet aggregation; omega-3s have antiplatelet activity at high doses.¹⁵⁷⁹ On an ordinary day that is invisible. During surgery, when the plan depends on knowing how a patient clots, it is information the team needs and usually does not have.

Two smaller mechanisms deserve their own mention. Several of these compounds inhibit cytochrome P450 enzymes — curcumin with piperine inhibits CYP3A4, CYP2C9 and P-glycoprotein, and can raise levels of many drugs including tacrolimus and some chemotherapies; resveratrol inhibits CYP3A4, CYP2C9 and CYP1A2 at higher doses.⁷⁹ And several add to sedation, which is not a bleeding question but is an anesthesia question.

The bleeding-risk cluster, graded by what is actually known

Compound	Concern	Evidence type	What the record says
Ginkgo biloba	Additive bleeding — highest concern in the category	Case reports; controlled PK studies more reassuring	Ginkgolides inhibit platelet-activating factor. Case reports of subdural hematoma, hyphema and intracerebral bleeding. Standard advice: clinician consultation with warfarin, DOACs, clopidogrel, aspirin and NSAIDs, and stop ≥2 weeks before surgery¹³
Omega-3 (high dose)	Antiplatelet activity at high doses	Trial data plus one case report	NIH ODS: most research shows 3–6 g/day fish oil does not significantly affect warfarin’s anticoagulant action, but INR should be monitored. A published case report describes a fatal outcome combining omega-3 with warfarin in traumatic brain injury. Several large CV trials also found a small consistent increase in incident atrial fibrillation at ≥1 g/day⁵⁶
Curcumin	Antiplatelet, plus CYP3A4/2C9/P-gp inhibition	Mechanistic and pharmacological	Caution with warfarin, DOACs, clopidogrel, aspirin. With piperine can raise levels of many drugs. Also a rising cause of drug-induced liver injury in US registries⁷⁸
Resveratrol	Platelet aggregation inhibition; CYP inhibition	Mechanistic	Caution with warfarin, DOACs, aspirin. CYP3A4/2C9/1A2 inhibition is clinically relevant at higher doses⁹
Saffron	Antiplatelet activity	Mechanistic; also serotonergic	Caution with warfarin, DOACs, aspirin, clopidogrel. Trials use 30 mg/day; toxicity at gram-level doses¹⁰
Vitamin E	Additive bleeding risk	Listed interaction	Grouped with the antiplatelet cluster in cross-cutting interaction references
Phosphatidylserine	Additive bleeding risk	Theoretical	Phospholipid effects on platelet membranes; commonly listed as a caution rather than observed¹¹
Lion’s mane	Antiplatelet activity	Theoretical	Caution with anticoagulants and antiplatelets pending data¹²
Panax ginseng	Reduces anticoagulant effect — lower INR	Case reports plus a controlled study	One of the better-documented herb–warfarin interactions, and it runs in the opposite direction from the rest of this table¹³¹⁴
CoQ10	Reduces anticoagulant effect — lower INR	Case reports	Structurally similar to vitamin K2. Monitor closely. Its cognitive evidence is weak enough that stopping it costs nothing¹⁵¹⁶
Acetyl-L-carnitine	Increases INR	Case reports	Monitor. Separately a peripheral antagonist of thyroid hormone action¹⁷

The “evidence type” column is the part to read twice. Ginkgo has published case reports of serious bleeds; phosphatidylserine and lion’s mane have a plausible mechanism and nothing else. Both end up on the same pre-op stop list, but for different reasons, and only one of them is a documented event.

Sedation, which is a different problem

Ashwagandha, L-theanine, magnesium and gotu kola are all listed as adding to the effects of CNS depressants.¹⁸ Nobody has studied any of them alongside modern anesthetic agents, and we are not going to imply otherwise — this is reasoning from a documented class interaction, not a measured one. It is still worth disclosing, because the anesthetist is titrating sedation against your response, and unexplained variance in that response is exactly what they do not want.

Ashwagandha carries a second reason to mention it: NIH LiverTox assigns it a likelihood score of B, a likely cause of clinically apparent liver injury, with latency typically 2 to 12 weeks.¹⁹ Perioperative liver enzyme abnormalities have enough possible explanations without an undisclosed one.

What to do, and when

Two weeks out: stop botanical supplements. That is the interval named for ginkgo and the one applied as a general rule for people on anticoagulants.¹ Two weeks is not a pharmacokinetic calculation for every compound on the list — it is a conservative default that clears the ones that matter.
At the pre-op appointment: hand over a written list, or the bottles. Include doses. “A brain supplement” is not usable information; “600 mg ashwagandha and 240 mg ginkgo daily since March” is.
Do not stop prescriptions yourself. Anticoagulants, thyroid medication, antidepressants — the decision to hold or continue those belongs to the prescriber and the surgical team, and stopping some of them abruptly carries more risk than continuing.
Afterward, restart deliberately. Ask when, rather than resuming on discharge day. If a wound is healing or you are on a new medication, the interaction picture has changed.

One consolation for anyone worried about losing ground during a two-week stop: for most of these compounds there is very little ground to lose. Cochrane’s 2026 ginkgo review, across 82 studies and 10,613 participants, found little or no effect in mild cognitive impairment and only modest, variable six-month effects in dementia.² CoQ10’s most decisive datum is a high-dose Parkinson’s trial terminated for futility.¹⁶ Stopping two weeks of either is not a meaningful loss.

What we don’t know

There is no trial that randomizes surgical patients to stop or continue a given supplement and measures blood loss, transfusion requirement or reoperation. Everything above is assembled from case reports, mechanistic pharmacology and the pharmacokinetic studies that exist for individual compounds — and for ginkgo, controlled pharmacokinetic work has been more reassuring than the case reports.¹⁴ The honest summary is that the risk is plausible, occasionally documented, cheap to avoid, and unquantified.

What would change our mind

A prospective perioperative cohort large enough to measure bleeding outcomes by disclosed supplement use, with platelet function testing at induction. If that showed no difference in estimated blood loss for ginkgo users who continued versus those who stopped, the two-week rule would look like superstition rather than prudence. Until someone runs it, the asymmetry decides: stopping a supplement with a small unproven benefit for two weeks costs nothing, and the downside it guards against is a bleed.

Frequently asked questions

Do I need to stop creatine before surgery?

There is no known interaction between creatine and anticoagulants, SSRIs or thyroid medication. One thing to flag rather than to stop: creatine raises serum creatinine, which can look like a kidney problem on a routine metabolic panel. Tell whoever orders your bloodwork that you take it.²⁰

Is a multivitamin a problem?

The relevant part is vitamin K, and the rule is consistency rather than avoidance — vitamin K intake affects warfarin, so erratic changes are worse than a steady intake. Iron-containing multivitamins also interfere with levothyroxine absorption and should be separated by four hours.

What about fish oil at 1 g a day — is that “high dose”?

The antiplatelet concern is dose-related and the studied territory is 3–6 g/day for the warfarin question. The atrial fibrillation signal in large cardiovascular trials appeared at ≥1 g/day and especially at 4 g. Either way, tell the team the dose rather than the category.⁵

I have surgery in three days and I have been taking ginkgo. What now?

Stop it and tell the surgical team today rather than on the morning. Three days is not two weeks, and the decision about whether that matters for your operation is theirs to make with information, not yours to make with a search engine.

Sources

These statements have not been evaluated by the Food and Drug Administration. Nothing here is intended to diagnose, treat, cure or prevent any disease.

This article is information, not medical advice. Talk to a doctor or pharmacist about your own situation, especially if you take prescription medication.