In medical terminology, "NKDA" is an abbreviation used to denote that a patient has "no known drug allergies." This abbreviation is commonly used in medical records, charts, and prescriptions to indicate that the patient has not reported any previous allergic reactions or adverse effects to any medications or drugs. The use of this abbreviation alerts medical professionals to be cautious when prescribing medication to patients who have a known history of drug allergies or adverse reactions.