D2.254 - Can a medication leave its mark on the skin?

Fixed Drug Eruption (FDE) is a skin reaction characterized by the appearance of well-defined erythematous lesions that reappear in the same locations after re-exposure to a specific drug.

Its incidence has increased in recent years, making it one of the four most common drug-induced cutaneous manifestations.

One of the biggest challenges is the growing diversity of drugs used in clinical practice, particularly in the context of polypharmacy and chronic diseases, which complicates the identification of the causative agent and the differential diagnosis.

We conducted a retrospective descriptive analysis between 2015 and 2025 in the Allergy Service at the Hospital Universitario de Burgos, collecting data from 123 patients who presented cutaneous reactions with an initial suspicion of FDE.

In these 123 patients, 65 prick skin tests, 81 epicutaneous tests, and 58 controlled drug exposures were performed. FDE was confirmed in 65 patients, was suggestive in 44 cases, and was ruled out in 9 patients. Five patients were unable to complete the study.

The average time between drug administration and the appearance of the skin reaction was 17 hours. The most frequent locations of the lesions were the hands, forearms, and penis.

Of the 32 drugs involved in the study, the most commonly implicated were amoxicillin, metamizole, etoricoxib, and paracetamol.

FDE represents a skin reaction that is difficult to diagnose due to the low yield of available skin tests.

Accurate identification of the causative drug is crucial for proper management, but the diversity of drugs used in patient treatment complicates the differential diagnosis.

For this reason, a complete and thorough medical history is essential to guide the diagnostic suspicion. The results of our diagnostic tests emphasize the importance of conducting a comprehensive evaluation, both through skin tests and controlled drug exposures, to confirm the diagnosis and prevent the recurrence of reactions in the future.