Background: Naproxen is a non-steroidal anti-inflammatory drug (NSAID), belonging to
propionic acid group, and its chemical structure is a 6-metoxi-metil-2-naftalenoacetic acid. Fixed drug
eruptions (FDE) have been rarely reported.
Objective: A 38-year-old woman referred that after 2 hours of taking 2 tablets of naproxen for a headache,
she developed several edematous and dusky-red macules, one on right forearm and the other two
in both thighs and she was diagnosed with FDE probably due to naproxen.
Methods: We performed patch testing (PT) (Nonweven Patch Test Strips Curatest®; Lohman & Rauscher International,
Rangsdorf, Germany), with ibuprofen (5% Petrolatum), ketoprofen (2.5% Petrolatum), naproxen and nabumetone (both
10% in DMSO) on the residual lesion of the forearm with naproxen and in both thighs with ibuprofen, ketoprofen and
Results: Readings at day 1 (D1) and day 2 (D2) showed negative results to ibuprofen, ketoprofen and nabumetone, but
were positive to naproxen in D1.
A single blind oral challenge test (SBOCT) with other propionic acid derivates were performed in order to check for crossreactivity
between them: ibuprofen, ketoprofen and nabumetone were administered and all drugs were well tolerated.
Conclusion: In our patient PT confirmed the diagnosis and allowed us to study the cross-reactivity between NSAIDs of
the same group, and confirmed by SBOCT. Cross-reactivity between propionic acid derivatives was studied. This is a case
of hypersensitivity to naproxen with good tolerance to other propionic acids NSAIDs (ibuprofen and ketoprofen) and
nabumetone, confirmed by PT and SBOCT. Some relavent patents for fixed drug eruption are discussed.