Objectives Enquiries to the drug information centre revealed that clinicians were not aware of the importance of rifampicin drug interactions. We conducted a short time study to demonstrate the relevance of these interactions in the clinical setting today.

Methods Over a total period of 4 weeks (two 2-week periods) we identified patients on rifampicin, performed a drug interaction test for their complete medication regime and analysed the results for severity of drug interactions.

Results A total of 137 potential drug interactions were found in 26 patients, including 6 contraindications. For additional 80 combinations, treatment adjustment was required or probably necessary. Most interactions had not been considered for the patient, including all contraindications and drug interactions with anti-infectives.

Conclusions Rifampicin drug interactions are of high relevance in the clinical setting today. However, clinicians failed to consider this issue for all patients. An individual drug interaction test is recommended for all patients given rifampicin. This is especially important when electronic patient records with integrated drug interaction tests are not available.