NKDA (no known drug allergies)
Formal Definition
"NKDA" — a standard chart abbreviation for "no known drug allergies," indicating that at the time of documentation the patient is not aware of any adverse immune-mediated reactions to medications; required for every encounter in the allergy section of the chart (typically as part of the medication reconciliation); distinct from "NKA" (no known allergies, referring to environmental and food allergies) and not a substitute for a thorough allergy history-taking.
How It's Used on the Ward
"NKDA" — what every med student, resident, and attending documents on a chart for a patient who reports no drug allergies; appears in the upper part of the chart, in the HPI template, and in every note; complacency about documentation can miss true drug reactions that the patient forgot or never linked to a medication.
Example
""Allergies box at the top of a new admission H&P for an otherwise healthy 45-year-old with appendicitis: 'NKDA. No known environmental or food allergies.' Patient denies any prior hives, anaphylaxis, or unusual reaction to antibiotics (including prior course of amoxicillin), NSAIDs, anesthetic agents, or contrast media. Anesthesia team queries allergy box, confirms NKDA, proceeds with general anesthesia for lap appy.""
Clinical Context
Best practice allergy documentation: (1) Specify allergen by generic name, not brand. (2) Specify reaction type — anaphylaxis, angioedema, urticaria, rash, GI upset, neurologic, etc. (3) Specify date or age if known. (4) Specify severity — fatal, ED visit, hospitalization, ER only, just stopped med. (5) Differentiate true allergy from intolerance (e.g., nausea from opioid is intolerance, not allergy — does NOT preclude use). Common examples documented: penicillin "rash" (often poorly characterized — may have been viral exanthem misattributed; skin testing can re-evaluate), opioids "itching" (often histamine-mediated, dose-related; not true allergy), iodine "allergy" (contrast is safe in shellfish allergy; not an allergy concept), NSAID-induced urticaria vs NSAID-exacerbated respiratory disease. "NKDA" should never preclude asking again at each encounter, especially pre-procedure or pre-op — patients sometimes recall reactions they did not initially report. Allergy module in EHRs is critical for medication safety; invalid entries (e.g., "acetaminophen — drug ineffective") can be entered but should be clearly characterized.