Final answer:
The priority nursing action when a client mentions a potential allergy to medication is to review the client's medical record for confirmation, followed by noting the allergy on the client's Kardex and informing the provider.
Step-by-step explanation:
When a client tells a nurse that she thinks she is allergic to a particular type of medication, the nursing action that has priority is to review the client's medical record for confirmation of the allergy. This is the most immediate action to ensure the safety of the patient, by verifying the allergy information in the medical record. After confirming the allergy, the nurse should note the allergy on the client's Kardex, which is an essential communication tool that ensures all healthcare team members are aware of the allergy. Informing the provider and educating the client to have all medications identified before taking them are also important steps but they follow the initial confirmation of the allergy.