See also Warning and How to Use sections.

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.

Ketoconazole interacts with many prescription and nonprescription drugs. While you are taking ketoconazole, it is very important to tell your doctor or pharmacist of any changes in medications that you are taking.

Some products that may interact with this drug include: other drugs that can cause liver problems (such as acetaminophen).

Other medications can affect the removal of ketoconazole from your body, which may affect how ketoconazole works. Examples include isoniazid, nevirapine, rifamycins (such as rifabutin, rifampin), St. John's wort, among others.

This medication can slow down the removal of many other medications from your body, which may affect how they work. Examples of affected drugs include some benzodiazepines (such as alprazolam, midazolam, triazolam), domperidone, eletriptan, eplerenone, ergot drugs (such as ergotamine), nisoldipine, drugs used to treat erectile dysfunction-ED or pulmonary hypertension (such as sildenafil, tadalafil), some drugs used to treat seizures (such as phenytoin), some statin drugs (such as lovastatin, simvastatin), among others.

Ketoconazole requires acid in the stomach to be well absorbed. If you are taking drugs that decrease the amount of stomach acid including antacids, heartburn/ulcer drugs (H2 blockers such as cimetidine, famotidine, ranitidine), sucralfate, or if you are taking drugs that slow down gut movement (anticholinergics such as dicyclomine, propantheline), take ketoconazole at least 2 hours before any of these drugs. If you are taking proton pump inhibitors (PPIs such as lansoprazole, omeprazole), ask your doctor or pharmacist for advice on how to reduce or avoid this interaction.

Ketoconazole is very similar to levoketoconazole. Do not use medications containing levoketoconazole while using ketoconazole.