Q: Many patients report a SULFA allergy–typically a rash. What is the chance that they will react to a diuretic like HYDROCHLOROTHIAZIDE
which as a sulfa moiety?
–Dr. L
Dear Dr. L
Skin testing to sulfa and many other drugs is not useful. The culprit-antigen is formed in the body when a breakdown product of the sulfa drug combines with a patient’s proteins. So I cheated a little and went to the Mayo Clinic website. This is a Quote:
“There are also a number of other medications related to sulfonamides. Although the medications noted below are probably safe for you to take if you have a sulfa allergy, you should first check with your doctor. Examples include, but are not limited to: Certain ‘water pills’ (diuretics), such as furosemide (Lasix) and hydrochlorothiazide (Microzide).”
So the cheating did not help me. I would like to know how bad the sulfa reaction was. Did the reaction occur with other sulfa drugs? If it did, how much medication was needed to cause a reaction? What was the time interval between taking the drug and having a reaction? This knowledge would help us do a challenge test.
We would give approximately a quarter dose of the DIURETIC and observe the patient twice as long as the time interval between taking the drug and having a reaction. Then we would increase the dose in a stepwise fashion until a full dose was reached without a reaction.
Dr. Chiaramonte
Asthma Allergies Children parent's web guide
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