In a patient treated for tuberculosis, which drug is likely to cause reddish urine?

Rifampin is known to cause reddish urine, which is a common side effect of this medication. This is due to its ability to change the coloration of bodily fluids as it is metabolized and excreted. The reddish hue occurs because rifampin has a chemical structure that allows it to impart color. This side effect can be alarming for patients who may not be aware of it, so education about the potential for discoloration of urine is important when initiating therapy.

In contrast, the other medications listed do not typically cause such a noticeable change in urine coloration. Isoniazid primarily affects liver function and may lead to hepatotoxicity without altering urine color. Pyrazinamide is mainly associated with liver issues and arthralgia, but does not change urine color. Ethambutol can cause visual disturbances but doesn't affect the coloration of urine. Understanding these distinctions helps in managing patient expectations and ensuring that any changes in urine color are not misinterpreted as symptoms of another underlying condition.