Table 1.

Aspects to be considered when documenting a case of a herb–drug interaction

Aspect	Specification
Characteristics of user	Age/gender/ethnicity
	(Co-)morbidity/anamnesis
Characteristics of herbal product/conventional drug	Composition/dosage form
	Phytochemical constituents/quality of herbal product
Use of herbal product/conventional drug	Reason for/duration of use
	Route of administration/dose/time and dose/day
Use of other products	Conventional/unconventional products
Characteristics of adverse event	Clinical signs/symptoms
	Laboratory findings
	Conventional drug levels
Evaluation of adverse event	Temporal time sequence
	Dechallenge/rechallenge
	Formal causality assessment
	Stability of patient before/after adverse event
	Coverage of existing literature
	Product-bound/user-bound/circumstances-bound risk modifiers (e.g. frailness/infrequent genotype)
Evaluation of confounding factors	Change in (co-)morbidity
	Change in intake food/alcohol/recreational drugs
	Change in conventional/unconventional products
	Change in patient adherence