Drug Interaction Severity Calculator

This calculator combines a clinician-supplied severity rating for each of two drugs with three risk multipliers into a single composite score. The two severity scores average together into a base score, which is then multiplied by the combined risk multiplier (how strongly the specific interaction is known to compound), the patient's age risk factor, and their renal risk factor. The five inputs fall into two structurally symmetric groups rather than all being interchangeable: the two severity scores average together and contribute identically to the base score, and the three multipliers (combined risk, age, renal) each apply the same 1x-3x scaling role to that base score. Because the multipliers compound -- each one's measured swing depends on whatever the other two happen to be set to -- their measured effect on the combined score at the default values isn't identical across all three (age and renal risk move the score more than the combined-risk multiplier does, near the defaults), but that reflects where each starts from rather than a real difference in how much clinical weight the calculator assigns to drug severity, age, or renal function; the calculator does not attempt to rank any one of the five as inherently more clinically significant than the others.

The combined score is then bucketed into a four-level risk classification (low, moderate, high, critical) that flags whether monitoring is recommended. This tool does NOT draw on a real drug-interaction database or a validated severity classification system (such as those used by clinical decision-support software) -- every input is a rating the user supplies from their own clinical judgment or from consulting a drug-interaction reference separately. Treat the output as a structured way to combine severity judgments you already have, not as an independent source of which drug pairs interact or how severely.