Successful Sequential and Additive Drug Challenge With Rapid Oral Desensitization in Rifampicin-Induced Fever.

Adverse drug reactions to first-line antituberculosis (anti-TB) therapy are common and may necessitate treatment interruption. While drug desensitization is increasingly used for delayed hypersensitivity, evidence supporting outpatient rapid oral desensitization in mild delayed reactions such as drug-induced fever is limited. We report a 63-year-old man with active pulmonary tuberculosis who developed drug-induced fever after commencing standard anti-TB therapy. Sequential and additive drug challenge identified rifampicin as the offending agent. The patient subsequently underwent successful rapid oral rifampicin desensitization in an outpatient setting, enabling completion of 6 months of therapy without recurrence of adverse effects. This case demonstrates the feasibility of outpatient rapid oral desensitization for mild delayed hypersensitivity reactions, including drug-induced fever. Such an approach may reduce treatment interruption and hospitalisation, particularly in settings where standardised outpatient desensitization protocols are lacking. Further studies are needed to define optimal strategies for managing mild delayed hypersensitivity reactions to anti-TB medications.