Multiple drug allergy syndrome (MDAS) is a clinical condition where a subset of drug-intolerant patients is prone to react against several chemically unrelated antibiotic or non-antibiotic drugs. The pathogenesis of MDAS is unclear and management often presents as a frustrating challenge. The authors describe a clinical case of MDAS.

27 years old female patient, followed at nephrology department, with a history of recurrent pyelonefritis referred to our clinic after several adverse reactions to antibiotics, in order to find an alternative therapeutic. A positive history of hypersensitivity to anti-inflammatory drugs was identified, tolerating paracetamol. Clinically all reactions occurred with dyspnea, vomiting and urticaria at different days of therapy considering the antibiotic involved. The reaction occurred at 7th day to cotrimoxazole; 6th day to gentamicyn; 5th day to amoxicillin; 4th day to ciprofloxacin and at 2nd intake to norfloxacin. The urine culture remained positive. It has been proposed a 10-day cotrimoxazole oral desensitization protocol. At the 6th day of therapy developed mild urticaria, which has been controlled with oral cetirizine (10 mg/day) for 3 days. This therapeutic scheme was successfully maintained with a prophylactic daily dose for 6 months.

In these patients, the 10-day cotrimoxazole oral desensitization protocol seems a safe and sensitive procedure to find alternative therapeutics. Urticaria may occur and should be treated throughout the duration of hypersensitivity.