A 66-year-old woman was initially seen in August 2009 with a 6-week history of a pruritic stinging eruption on her upper extremities and upper trunk. She reported having experienced a similar eruption approximately 8 years previously that was suspected to have been caused by hydrochlorothiazide use and had resolved approximately 9 months following discontinuation of this medication, without additional therapy. She denied recent hydrochlorothiazide ingestion; her only new medication in the months before the current episode was intermittent furosemide use for lower extremity swelling. Her medical history included hypertension, parkinsonism, rheumatoid arthritis, and anxiety and depression. Her other medications at presentation included atenolol, gabapentin, nisoldipine, carbidopa-levodopa, bupropion hydrochloride, trazodone hydrochloride, citalopram hydrobromide, duloxetine hydrochloride, ziprasidone hydrochloride, and oxycodone hydrochloride–acetaminophen, as well as multivitamins, ω-3 fish oil, and calcium supplementation. Physical examination revealed scaly, annular, erythematous plaques in a photodistribution on the arms, legs, and upper trunk. A punch biopsy specimen was obtained, demonstrating increased dermal mucin, thickened basement membrane, and vacuolar interface dermatitis with an associated perivascular and perifollicular lymphohistiocytic infiltrate. Rare tissue eosinophils were noted. The results of her complete blood cell count with differential cell count and comprehensive metabolic profile with liver function studies were normal, except for a marginally elevated serum creatinine level of 1.2 mg/dL (reference range, 0.6-1.0 mg/dL) (to convert creatinine level to micromoles per liter, multiply by 88.4). Serological test results showed a positive antinuclear antibody (ANA) (titer and pattern not reported), an elevated antihistone antibody level at 1.3 U (reference range, 0.0-0.9 U), an elevated anti-La/SS-B antibody level at 5.5 arbitrary units (AU) (reference range, 0.0-0.9 AU), and an elevated anti-Ro/SS-A antibody level exceeding 8.0 AU (reference range, 0.0-0.9 AU). Test results for anti-Smith antibodies, anti-ribonucleoprotein antibodies, and anti–double-stranded DNA antibodies were normal. To our knowledge, urinalysis was not performed. She was diagnosed as having SCLE exacerbated by furosemide use, and her disease gradually resolved 2 months after discontinuation of the drug using photoprotection and twice daily triamcinolone acetonide, 0.1%, cream.