Rifampicin increases the excretion of
dapsone, lowers its
serum levels and increases the risk of
toxicity (methaemoglobinaemia).
Concurrent use should be well monitored to confirm that treatment is effective. It may be necessary to raise the dosage of
dapsone. It has been pointed out that there is a risk of treatment failure for pneumocystis pneumonia as well as for leprosy. Also be alert for any evidence of
dapsone toxicity (methaemoglobinaemia).