Anesthesia and Potential Herbal Drug Interactions: Mini-Review

 In Naturopathic News

A “mini-review” on herb-drug interactions(1) published late in 2016 ushers a reminder to the naturopathic profession that the conventional medical profession is changing, with an ever-increasing interest in natural products, herbal remedies and holistic therapies. This review, while very well researched, also serves as an example of the deficit the conventional medical system has when it comes to these therapies – there is a lack of overall understanding and robustness of the information they are producing in these areas. Naturopaths are the experts in this field. Awareness of the research and publications, which may be either supporting or refuting the efficacy of herbal and other naturopathic therapies, as well as additional well-researched resources from the naturopathic profession for our conventional colleagues is of vital importance.

The article at hand, Phyto-anesthetics: A mini-review on herb-anesthesia drug interactions, very succinctly explains the 3 primary mechanisms of action of herb-drug interactions. It is a good reminder. Herbal remedies primarily affect drug pharmacodynamics through altered regulation of the three phases of detoxification through the gastro hepatobiliary system.

Phase to Phase Results

In phase I, the oxidative action of CYP monooxygenase on xenobiotics is either enhanced or suppressed, leading to changes in metabolism of other drugs (and supplements). St. John’s wort is a well-known inducer of CYP 3A4 activity,(2). Phase II influences include changes in the gastrointestinal pH and dissolution properties, which can alter the absorption of pH-dependent drugs such as ketoconazole and itraconazole (commonly used antifungals). Herbs such as cassia, cascara, rhubarb and soluble fibers alter gastric motility as well as bind xenobiotics in insoluble complexes inhibiting absorption. Phase III inhibition of transporter proteins such as ATP-binding cassette (ABC) transporter and P-glycoprotein by natural compounds changes the pharmacokinetic profile of a drug.  “Pharmacokinetic interaction occurs when herbal drugs inhibit or decrease the normal activity level of drug transporters through a competitive or non-competitive mechanism.”(1) Some common clinically important P-gp inhibitors include – flavonoids, furanocoumarins, reserpine, quinidine, yohimbine, vincristine, vinblastine among others.

A short list of herbs is included in the review, along with referenced drug interactions

As stated above, this is a great opportunity to acknowledge the manner in which allopathic physicians view these herbal agents, and for us to supplement this information. Francis Brinker, ND has researched all of these herbs extensively, and comprehensive, well-researched information can be found in the fourth edition of “Herbal Contraindications and Drug Interactions: Plus Herbal Adjuncts with Medicines.”(2)

Listed in Article:

Ginseng – Decreases blood concentration of Warfarin. Increases effects of Chlorpropamide leading to hypoglycemia (mania is listed in the article’s table). Interacts with Phenelzine sulfate.
Ginkgo Biloba – Increases bleeding risk when taken with anticoagulant agents such as Warfarin, ticlopidine, clopidogrel, Dipyridamole. Also interacts with Trazodone and can increase “off” periods in Parkison’s patients on Levodopa.
Garlic – Can further increase bleeding time when taken with Warfarin. Interacts with general anesthetics  Also may have antagonistic effect on immunosuppressing medications
Ginger – Alters bleeding time when taken with Warfarin. Reduces the side effect profile (nausea) of chemotherapy agents
Goldenseal– Increases blood concentrations of Debrisoquine and Midazolam.
Kava – Has an additive effect on anti-Parkinson drugs hepatotoxic drugs. May increase risk of developing liver damage
Milk Thistle – Reduces liver toxicity from acetaminophen, Cyclosporine, Cisplatin.
Black Cohosh – Interacts with oral contraceptives, Tamoxifen. Increases bleeding potential when taken with Warfarin; contains coumarin constituents.
Chilli Pepper – Increases side effect of cough with ACE inhibitors. Increased absorption and bioavailability of ACE inhibitors and Theophylline.
Shankhapushpi – Decreases concentration of Phenytoin, with a loss of control of seizures.
Psyllium – Decreases concentration of Lithium
Licorice – Decreases plasma clearance of Prednisolone, Hydrocortisone, and oral contraceptives. Increases plasma concentration of steroids, and potentiates cutaneous vasoconstrictor response. Possible side effects listed are hypertension, edema and hypokalemia (no blood pressure medications listed)
Karela or Bitter Melon – additive effect with Chlorpropamide; less glycosuria.
Aloe – Increases potential for potassium loss with Thiazide diuretics. Increases laxative effect when taken with laxatives. May potentiate hypoglycemia when used with antidiabetic agents. Interacts with Digoxin
Flaxseed – Original chart actually says: “ These products should not be taken with other dietary supplements or medications because the high fiber content may lower the body’s capacity for absorption.”
St. John’s Wort – Decreases blood concentrations of Cyclosporine, Midazolam, Tacrolimu, Amitriptyline, Digoxin, Indinavir, Warfarin, Phenprocoumon, Theophylline, Irinotecan, Alprazolam, Dextromethorpha, Simvastatin, Sertraline, Paroxetine, and Nefazodone Antidepressant or serotonergic drugs. Potential for serotonin syndrome, gastrointestinal disorder, allergic reactions, fatigue, dizziness, confusion, dry mouth, photosensitivity.


  1. Vahabi S, Eatemadi A. Phyto-anesthetics: A mini-review on herb-anesthesia drug interactions. Biomed Pharmacother. 2016;84:1885-1890. doi: 10.1016/j.biopha.2016.10.100.
  2. Brinker F. Herbal Contraindications and Drug Interactions: Plus Herbal Adjuncts with Medicines. 4th edition. Sandy, OR: Eclectic Medical Publications; 2010.

    Node Smith, associate editor for NDNR, is a fifth-year naturopathic medical student at NUNM, where he has been instrumental in maintaining a firm connection to the philosophy and heritage of naturopathic medicine amongst the next generation of docs. He helped found the first multi-generational experiential retreat, which brings elders, alumni, and students together for a weekend campout where naturopathic medicine and medical philosophy are experienced in nature. Three years ago he helped found the non-profit, Association for Naturopathic ReVitalization (ANR), for which he serves as the board chairman. ANR has a mission to inspire health practitioners to embody the naturopathic principles through experiential education. Node also has a firm belief that the next era of naturopathic medicine will see a resurgence of in-patient facilities which use fasting, earthing, hydrotherapy and homeopathy to bring people back from chronic diseases of modern living; he is involved in numerous conversations and projects to bring about this vision. 

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