The fixed drug eruption always occurs in the same spot, often with pain and burning, hours to days after taking the offending pill.

Fixed drug eruptions may be multiple.

FIXED DRUG ERUPTION

The fixed drug eruption (FDE) is an unusual allergic reaction usually to an oral medication in which one round or oval area of the skin inflames each time the offending agent is consumed. Multiple lesions may occur.

• The penis is a commonly involved site
• Prescription and OTC medications or the most common offenders, but rarely foods may be causative.
• It is often up to the patient to figure out the cause. This may require several days of reflection and even multiple episodes.

Clinical

Single or multiple, dusty-red, round, or oval lesions occurring repeatedly in a fixed site after each exposure to the offending drug is characteristic of a FDE. Pain or burning is common.

The glans is the most commonly involved site, but lesions may occur virtually anywhere, including the lips and oral mucosa. With each subsequent exposure to the drug, the initial lesion may increase in size, and additional lesions may develop. Crusting or blistering may occur. A hyperpigmented patch is often left which fades over months.

Example Drugs

• Antibiotics: sulfa, tetracyclines, quinolones
• NSAIDs: naproxen, ibuprofen, aspirin
• Acetaminophen
• Barbiturates
• Oral contraceptive pills
• Antihistamines
• Proton pump inhibitors
• Antifungals
• Phenolphthalein (obsolete laxative)
• Anti-epileptic drugs: carbamazepine

Example Non-Drugs

• Foods: strawberry, kiwi, peanut, cashew, asparagus, seafood, lentils, licorice
• Lactose, may be an additive in medications
• Quinine in tonic water
• Yellow food coloring additives (tartrazine and quinoline), achiote dye
• Influenza and COVID-19 vaccines
• Alcohol
• Ultraviolet radiation

Additional Pictures

Fixed drug eruption of the penis.

RegionalDerm

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