Medications · Supplements
Herbal Supplements Before Surgery
Herbal supplements feel gentle, but several genuinely matter around surgery — some thin the blood, and St John's Wort interferes with anesthetic drugs. The rule of thumb: stop them in good time and tell your team everything.
The short answer
Why herbal supplements matter
Two things make herbal products relevant around surgery. First, bleeding: garlic, ginkgo, ginseng and ginger all reduce the blood's ability to clot. Second, drug interactions: St John's Wort (taken for low mood) revs up the liver enzymes that process many medicines, which can change how your anesthetic and pain relief behave.
| Herbal supplement | Why it matters |
|---|---|
| Garlic (supplement dose) | Thins the blood |
| Ginkgo biloba | Thins the blood |
| Ginseng | Thins the blood; can affect blood sugar |
| Ginger (supplement dose) | Thins the blood |
| St John's Wort | Interacts with anesthetic & other drugs |
When to stop
About 1–2 weeks before surgery is the usual cautious window. Because supplement strengths vary and labels can be vague, the safest move is to bring the actual products (or a photo of the labels) to your pre-op visit and let your team advise.
Frequently asked questions
Which herbal supplements should I stop before surgery?
The classic blood-thinning herbs are garlic, ginkgo, ginseng and ginger (sometimes called the '4 G's'), usually stopped about 1–2 weeks before. St John's Wort is also stopped because it interacts with anesthetic and other drugs. When unsure, disclose it and ask.
Why does St John's Wort matter for anesthesia?
St John's Wort speeds up the liver enzymes that break down many medicines, which can change how anesthetic and other drugs work, and it can interact with them in other ways. Because of this it's usually stopped a week or two before surgery — tell your team if you take it.
Are herbal teas a problem before surgery?
Occasional herbal teas are generally not the concern — it's concentrated supplement capsules and extracts taken regularly. Still, mention anything you take routinely, since 'natural' products can have real effects.