Background and Objective: The recurrence of drug allergy was classified as preventable drug related problem might result in life- threatening allergic symptoms. The difference in drug allergy knowledge and understanding might lead to an awareness of drug allergy and drug allergy card carried by patients. The aim of the study was to assess the knowledge, understanding of drug allergy and drug allergy card carrying behavior of patients with drug allergy in Srinagarind Hospital.

Methods: A 3-month cross- sectional descriptive study was conducted. Self- administered questionnaires was distributed by post to drug allergic patients from pharmacy database and patients who were diagnosed with anaphylaxis, maculopapular rash, erythema multiforme, Stevens- Johnson syndrome and toxic epidermal necrolysis.

Results: A total of 288 questionnaires were evaluated. There were 137 patients (47.9%) had moderate knowledge level (mean±S.D. 3.19±1.03; total score of five). Moreover, 38.8% of the patients were unable to address the name of allergic drug and 85.7% of them answered the importance of drug allergy card incorrectly. The management of drug allergy was answered correctly in 86.4% of the patients.  The majority of patients (76.1%) always carried their drug allergy cards and about 73.3% of the patient always showed their drug allergy card at health care services. Furthermore, 40.3% of the patients had received their drugs from non- healthcare professionals.

Conclusion: Most of the patients knew the management of drug allergy. However, one- third of patients failed to recall the name of allergic drug and neglected to carry drug allergy card all the time. The continuing patient education might improve drug allergy knowledge and drug allergy card carrying behavior.

Keywords: knowledge, understanding, behavior, drug allergy, drug allergy card