Warnings & Interactions of Herbs

, December 2, 2015 in Therapeutics

You will notice that our single herbal products have numbers & letters assigned to them corresponding to Warnings & Interactions. This paper explains what each of the numbers and/or letters implies.

Herbs that can be safely consumed when used appropriately.
• History of safe traditional use
• No case reports of significant adverse events with high probability of causality
• No identified concerns for use during pregnancy or lactation
• No innately toxic constituents
• Toxicity associated with excessive use is not a basis for exclusion from this class
• Minor or self-limiting side effects are not bases for exclusion from this class

Herbs for which the following use restrictions apply, unless otherwise directed by an expert qualified in the use of the described substance:

2a: for external use only
• Toxicity demonstrated with crude preparation taken orally at traditional dose
• Adverse event data in humans with probability of causality of toxicity (eg. hepatotoxicity, nephrotoxicity, neurotoxicity) associated with oral use

2b: Not to be used during pregnancy
• Traditional use contraindicates
• Traditional use as an abortifacient or uterine stimulant
• Relevant adverse even data in humans exist and have probability of causality
• Data in animals suggesting teratogenicity or other adverse effects on the fetus or mother, with reasonable application to humans
• For plants with common food uses, standard dose is in excess of typical food amounts

2c: Not to be used while nursing
• Traditional use contraindicates
• Relevant adverse event data in humans exists and has probability of causality
• Potential hepatotoxicity or neurotoxicity
• Bioavailability of constituents of concern in breast milk has been demonstrated

2d: Other specific use restrictions as noted
• Information exists that use may be unsafe for specific populations
• Dosage level outside of a standard range known to cause adverse effects

Herbs to be used only under the supervision of a qualified expert. The following labelling is recommended for Class 3 herbs: “To be used only under the supervision of an expert qualified in the appropriate use of this substance. “ Labelling must include proper use information:
dosage, contraindications, potential adverse effects and drug interactions, and any other relevant information related to the safe use of the substance.
• Narrow therapeutic range
• Identified safety concerns in many populations


Herbs for which no clinically relevant interactions are expected.
• No case reports of suspected interactions with probability of causality
• No clinically relevant interactions in human pharmacological studies, if any,

Herbs for which clinically relevant interactions are biologically plausible
• Human or animal pharmacological study data suggest potential for clinically relevant interaction.
• Multiple case reports have suggested a potential interaction concern.
• Cell culture or biochemical assays establish a basis for biologically plausible mechanism of interaction.

Herbs for which clinically relevant interactions are know to occur
• Human pharmacological study has demonstrated interaction with a specific drug or supplement.
• Human pharmacological study has demonstrated clinically relevant effects on drug metabolizing enzymes or drug transporter proteins.
• Case reports of suspected interactions have a probability of causality.

all of our safety information is from:
The Botanical Safety Handbook
Second Edition
Edited by: Zoë Gardner, Michael McGuffin
Expert Advisory Council: Roy Upton, Soaring Bear, David Winston, Daniel Gagnon, Aviva Romm, Tieraona Low Dog, Mary Hardy, Lyle Craker