Yellow dye was to blame. In our case, the 20-mg tablet that the patient had been taking contained the coloring agent FD&C yellow #6, an azo dye also known as sunset yellow or E-110 in Europe. Several reports have described adverse reactions to this coloring agent.1,3 There were other additives in the 20-mg tablet, but a comparison revealed that the 10-mg tablet contained identical substances—but no dye. Thus, it was most likely that the coloring agent was the cause of the patient’s probable type IV exanthematous drug reaction.
Our patient
The patient was instructed to avoid all medications and food containing FD&C yellow #6. No formal allergy testing or re-challenge was performed, since the patient did well under the care of his nephrologist.
THE TAKEAWAY
It’s important to recognize that adverse drug reactions can occur from any medication—not only from the drug itself, but also from excipients contained within. This case reminds us that when a patient complains of an adverse effect to a medication, dyes and inactive ingredients need to be considered as possible inciting agents.
CORRESPONDENCE
Neil E. Soifer, MD, Lakeside Nephrology, 2277 West Howard, Chicago, IL 60645; nsoifer@aol.com