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Category: Medical

Topic: Pharmacology

Level: AEMT

Next Unit: Stimulants

16 minute read


Dietary supplements and herbal preparations are not required to prove their efficacy by any regulatory agencies; instead, legislation has made it necessary for the burden of proof to be on the FDA to DISPROVE efficacy. Hence, many preparations are allowed to make health claims (e.g., "promotes prostate health") as long as it also says, "this product is not intended to diagnose, treat, cure, or prevent disease." This is the perfect don't-ask-don't-tell side-stepping of scrutiny based on--not evidence--but capitalism and labeling loopholes. In fact, manufacturers of herbal preparations and supplements are not even required to report postmarketing adverse events. Also, when herbal preparations are labeled "standardized," there is still significant variation in formulation.

Nevertheless, herbs are pharmacologically active and therefore can positively and negatively impact patient health. Just because herbal preparations come from plants does not make them automatically safe. (Otherwise, nicotine--and hemlock!--would be safe.) The compatibility of the plants used in the herbal preparations, the manufacturing procedures, and the potential for contamination all impact the efficacy and safety of the compound on the body.

Adulteration: the process of substitution of genuine plants with other plants that have similar effects to save money. Adulteration happens when there is a high demand and not enough sustainable sources.


Herbal Preparations and Supplements


Many common herbs offer benefits:

  • Soy: for hypercholesterolemia.
  • Ginger: as an anti-emetic.
  • Probiotics: for ulcerative colitis, infectious diarrhea, and irritable bowel syndrome.
  • Fish oils (with omega-3 fatty acids): for reduction of cardiovascular risk.


Issues for herbs include adverse effects and drug-herb interactions. The belief among some patients that "more is better" leads to significant side effects and harm from ingesting large amounts of herbal products. For example, toxicities due to overuse have been documented with ginseng and licorice.


Ephedra: has been outlawed in supplements, but still may be present in foreign-marketed preparations. Manufacturers have substituted synephrine from bitter orange in weight loss products. Ephedra-like untoward events include:

  • hypertension,
  • arrhythmias,
  • myocardial infarction,
  • stroke, and
  • seizures.

Kratom (Mitragyna speciosa): for self-treatment of opioid withdrawal, with risks of:

  • over-dose death,
  • addiction,
  • respiratory depression,
  • anorexia,
  • depression,
  • psychosis, and
  • seizures.

Herbs Affecting Blood Sugar

Causing hypoglycemia:

  • Alfalfa
  • Aloes/Aloe vera
  • Celery
  • Eucalyptus
  • Garlic
  • Ginger
  • Ginseng
  • Juniper
  • Myrrh
  • Sage

Causing hyperglycemia:

  • Devil's claw
  • Elecampane
  • Figwort
  • Ginseng
  • Hydrocotyle
  • Licorice

Herbs Affecting Hormones

  • Alfalfa (estrogenic)
  • Aniseed (estrogenic)
  • Cohosh, black (estrogenic)
  • Ginsengs (estrogenic)
  • Horseradish (depresses thyroid activity
  • Liquorice (sodium retention; estrogenic)
  • Motherwort (oxytocic--uterine contractions)
  • Red clover (estrogenic)
  • Saw palmetto (estrogenic and anti-androgenic)
  • Vervain (inhibition of gonadotropins)
  • Wild carrot (estrogenic)

Herbs Causing Hypotension

  • Grapefruit juice [SEE BELOW]

Herbs Causing Hypertension

  • Bayberry
  • Capsicum
  • Cohosh, blue
  • Gentian
  • Ginger
  • Ginseng
  • Licorice
  • Maté
  • Vervain

Herbs Affecting the Heart

  • Devil's Claw
  • Figwort
  • Ginger
  • Ginseng
  • Mistletoe
  • Motherwort
  • Parsley
  • Prickly ash
  • Quassia
  • Shepherd's purse
  • Squill
  • Wild carrot


Herb-Drug Interactions

  • St. John's Wart: metabolizes drugs such as immunosuppressants, oral contraceptives, warfarin, and digoxin, leading to their failure in treating specific illnesses. It can also lead to higher lead blood levels, especially in preparations manufactured overseas.
  • Ginko Biloba: has antiplatelet and anti-thromboitc effects and can interact with warfarin, NSAIDs, and aspirin, leading to a risk of spontaneous bleeding and hemorrhage.
  • Grapefruit juice: may elevate plasma concentration of calcium channel blockers (verapamil/Calan, diltiazem/Cardizem), causing hypotension.



DIETARY SUPPLEMENTS: Most people feel that vitamins are good no matter what. In this mindset, they may feel more is better. However, too much of a "good thing" can cause problems, especially with vitamins.

  • Vit D: hypercalcemia, confusion, polyuria, polydipsia, anorexia, vomiting, muscle weakness, nephrocalcinosis, bone demineralization, pain. High doses of vitamin D of 10,000 to 50,000 units daily may be necessary to replete vitamin D in some patients. Such patients require careful monitoring to avoid toxicity.
  • Vit A: acute toxicity with >660,000 IU--nausea, vomiting, vertigo, blurry vision, drowsiness, malaise; chronic toxicity with doses 10x recommended daily allowances--dry skin, nausea, headache, fatigue, irritability, hepatomegaly, alopecia, increased cerebrospinal fluid levels, and hepatotoxicity leading to cirrhosis.


In the Field

In the field, herbal preparations will impact, mostly, diabetic patients, cardiac patients, and those on anticoagulants. Regardless of what leads to the call for help, any emergencies for coagulation-related or cardiac incidents require rapid transport. Patient on anti-coagulants as well as recently post-op and postpartum patients are at risk for the anticoagulant potentiation of supplements. Still, you're not going to go through a checklist that includes the question, "Hey, have you been using too much Devil's Claw?" Your call to action is to stabilize this patient like any other, transport to a facility where the fine details can be sorted out, and to document, when time and safety allows, what herbals and supplements are reported by the patient. 

With the exception of grapefruit ingestion with calcium-channel blockers (⇒ hypotension), most herb-drug interactions cause hypertension.

All that being said, if you must ask about any of them, here are The Big Five:

  1. St. John's Wart (Herbal-Drug Interactions)
  2. Ginko Biloba (Anticoagulation)
  3. Ephedra-like substances,
  4. Grapefruit juice, and
  5. Kratom (Mitragyna speciosa, in opioid abusers)

A good resource for ingredients of herbal preparations is the Dietary Supplement Labels Database:


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