See also How to Use section.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Rifampin interacts with many medications. While you are using rifampin, it is very important to tell your doctor or pharmacist of any changes in medications that you are taking.

Rifampin can speed up the removal of other medications from your body, which may affect how they work. Examples of affected drugs include atovaquone, certain anti-cancer drugs (such as irinotecan), certain azole antifungals (such as itraconazole), certain calcium channel blockers (such as nifedipine), certain products used to treat chronic hepatitis C (such as sofosbuvir), cobicistat, lurasidone, HIV NNRTIs (such as etravirine, nevirapine), praziquantel, HIV protease inhibitors (such as atazanavir, darunavir), among others.

This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Discuss with your doctor or pharmacist if you should use reliable backup birth control methods while using this medication. Also tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well.

This medication may interfere with certain lab tests (such as urine screening for opiates, blood serum folate/vitamin B12), possibly causing false test results. Rifampin may also make it harder for your body to get rid of certain chemicals used in gallbladder tests. Make sure lab personnel and all your doctors know you use this drug.