A case of serum sickness-like reaction and anaphylaxis - induced simultaneously by rifampin.

Rifampin is commonly used as a first-line anti-tuberculosis drug, but it can induce a serum sickness-like reaction or anaphylaxis. However, it is possible for 1 drug antigen to induce 2 or more simultaneous immunologic reactions. Here, we report a case of a serum-sickness-like reaction and anaphylaxis induced concurrently by rifampin. A 25-year-old male presented with high fever and a maculopapular rash with vesicles on the hands, which developed 2 weeks following regular administration of anti-tuberculosis drugs for tuberculous meningitis, including rifampin. Elevated liver enzymes, peripheral neuropathy, and decreased serum C3 and C4 levels were found. Interestingly, these symptoms were accompanied by severe hypotension. A serum-sickness-like reaction was considered after excluding other potential causes for the fever. A drug provocation test showed that the fever developed after oral administration of rifampin, suggesting that rifampin was the cause of the allergic reaction. However, hypotension, epigastric discomfort, and diarrhea also accompanied these symptoms, indicating that IgE-mediated type I hypersensitivity could be part of the serum sickness-like reaction. An intradermal skin test clearly showed an immediate positive reaction to rifampin. This case was diagnosed as concurrent serum-sickness-like reaction and anaphylaxis induced by rifampin. One drug may therefore induce combined allergic reactions via 2 or more simultaneous hypersensitivity responses.