Herbal medicines + surgery = risky

Chinese herbal medicines. Source: Wikimedia Commons.
Chinese herbal medicines. Source: Wikimedia Commons.

People should stop taking herbal remedies two to three weeks before surgery, because some natural remedies can lead to excessive bleeding, heart instability or a redusction in blood sugar levels, American researchers cautioned.

A study, published in the July 11th issue of The Journal of the American Medical Association (JAMA), reports that garlic, ginkgo and ginseng can lead to excessive bleeding, ephedra can cause cardiovascular instability, and ginseng can cause low blood sugar levels.

Researchers reported on the possible side-effects of the eight most commonly used herbal remedies used in the US: echinacea, ephedra (also known as ma huang), garlic, ginkgo, ginseng, St. John's wort, and valerian.

Additionally, the researchers reported that drug-herb interactions may result between anesthesia and valerian. These herbs, used as sleep aids, may increase the sedative effects of anesthesia.

Herbs are medicines, and some can have a profound effect when mixed with other medications, particularly those used before, during and after surgery.

Facts about use of herbal remedies

Researchers are concerned about the fact that one third of patients having surgery use herbal remedies but 50 % to 70 % of these patients do not inform their doctors that they use herbal remedies medications.

It is very important that patients should inform their physicians that they use natural remedies. Physicians are also becoming more educated about the use of alternative therapies.

The American Society of Anesthesiologists have suggested that patients stop taking herbal medications two to three weeks before surgery. In the US – and in South Africa – most anaethetists only see patients the day of surgery. Patients should inform their doctor as far in advance of surgery as possible.

Some herbal remedies should not be stopped abruptly. For example valerian could be associated with withdrawal if it is stopped abruptly in someone who has been taking it for a long time, researchers said.

The findings of the study include a list of concerns and recommendations for pre-operative patients:


Concerns: allergic reactions, affects immunosuppressive drugs; impairs wound healing.

Recommendation: discontinue as far in advance of surgery as possible, particularly if liver dysfunction or an organ transplant is involved.

Ephedra (ma huang)

Concerns: increases risk of heart attack, heart rhythm abnormalities, stroke and interaction with other drugs.

Recommendation: discontinue at least 24 hours before surgery.


Concerns: increases risk of bleeding, particularly if anti-clot medications are used.

Recommendation: discontinue at least seven days before surgery.


Concerns: increases risk of bleeding; interferes with anti-clot medications.

Recommendation: discontinue at least 36 hours before surgery.


Concerns: reduces blood sugar levels; increases risk of bleeding; interferes with warfarin, a popular anti-clot medication.

Recommendation: discontinue at least seven days before surgery.

St John's wort

Concerns: alters metabolism of many other drugs.

Recommendation: discontinue at least five days before surgery.


Concerns: could increase effects of sedatives; long-term use could decrease the amount of anesthesia normally used; severe withdrawal symptoms.

Recommendation: if possible, taper dose in weeks before surgery, or continue use until surgery and medically treat withdrawal symptoms.

There is no standard dosage that consumers can rely on. Every crop is different, every product is different, so it's very difficult sometimes to know the exact way an herb is going to affect someone having surgery, researchers said.

Read more:
Why herbs?
How safe are herbal medicines?

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