Some diagnoses announce themselves with a classic history and presentation. Fixed drug eruption is one of them.
Fixed drug eruption is a medication reaction that recurs in the same location every time the offending drug is taken. Patients develop one or a few sharply defined round or oval, red, violaceous, or dusky patches or plaques, often within hours of drug exposure. Common sites include the lips, hands, feet, and genital area, but any skin location is possible.
The eruption may initially appear as a solitary round or oval patch and can become swollen, blistered, or eroded. After it resolves, lingering hyperpigmentation often marks the spot, creating a clue for the site of future episodes. Additional patches or plaques may develop with each episode.
The Diagnostic Pearl
When a patient reports that a lesion keeps coming back in exactly the same place, think fixed drug eruption.
That history is often more revealing than the morphology alone.
Common Medication Triggers
Many medications have been implicated, but frequent culprits include:
- NSAIDs (such as ibuprofen and naproxen)
- Acetaminophen
- Antibiotics, particularly sulfonamides and tetracyclines
Always ask about prescription medications, over-the-counter products, and supplements taken in the days before the eruption appeared.
Why It Matters
Fixed drug eruption is commonly mistaken for irritant or allergic contact dermatitis, recurrent herpes simplex, insect bites, or other inflammatory dermatoses. Recognizing the characteristic pattern of recurrence can spare patients unnecessary testing and repeated episodes.
The Key is Simple:
If the lesion keeps returning to the same spot, look for the medication that keeps returning too.
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