After taking rifampicin, urine will turn red and orange, mainly because after rifampicin is absorbed and metabolized by the human body, its metabolites are excreted through urine, and the metabolites of rifampicin present an orange-red color, resulting in the urine will turn red. Rifampicin is a common anti-tuberculosis drug, belonging to the macrolide antibiotic, with strong antibacterial activity against Mycobacterium tuberculosis. After oral administration of rifampicin, two metabolites can be produced in the body, one is the product of the hydrolysis of the ester bond on the structure, called deacetyl rifampicin, and the other is aldehyde-based rifampicin, both metabolites have a certain degree of anti-tuberculosis activity, which is weaker than rifampicin. However, both metabolites contain structures that produce a red pigment, both appearing as an orange-red color, thus causing the urine to turn red when excreted through the urine.