Table 1.

Lexicomp® drug-drug interactions rating scales and corresponding categories and definitions.

Rating Scales	Categories
Risk Rating: indicates the level of urgency and the actions necessary to respond to an interaction.	A: No known interaction
	No evidence to support pharmacodynamic or pharmacokinetic interactions.
	B: No Action Needed Evidence demonstrate that two drugs may interact with each other, but there is little to no clinical data to support it.
	C: Monitor Therapy
	Evidence suggest that the two drugs may interact with each other in a clinically significant manner. The benefits of concomitant use of these two medications usually outweigh the risks. An appropriate monitoring plan should be implemented to avoid potential negative outcomes.
	D: Consider Therapy Modification
	Evidence suggests that the two medications may interact with each other in a clinically significant manner. Specific actions must be taken to minimize the toxicity resulting from concomitant use of the medications.
	X: Avoid Combination
	The interaction of the two drugs is of clinical significance. The risks of concomitant use of these drugs usually outweigh the benefits and generally contraindicated.
Severity Rating: indicated the magnitude of an interaction outcome	Major: the interaction is possibly life-threatening or may cause permanent damage
	Moderate: the patient’s condition may deteriorate due to the interaction. Additional care may be required.
	Minor: an interaction that is inconvenient, but otherwise not medically detrimental.
Reliability Rating: indicates the quantity and nature of documentation for an interaction.	Poor; Fair; Good; Excellent.

Adapted from: https://www.wolterskluwercdi.com/facts-comparisons-online/user-guide/tools-interactions/ accessed Feb 1^st, 2019.