Ketoconazole and Tadalafil interaction
Ketoconazole and Tadalafil: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Ketoconazole label · effective 2026-07-07
Respiratory Drugs salmeterol Urological Drugs fesoterodine, sildenafil, solifenacin, tadalafil, tolterodine, vardenafil Vardenafil: A single dose of 5 mg of vardenafil should not be exceeded when coadministered with ketoconazole.
From the Tadalafil (Cialis) label · effective 2026-06-03
Ketoconazole (200 mg daily) increased tadalafil 10-mg single-dose exposure (AUC) by 107% and C max by 15%, relative to the values for tadalafil 10 mg alone [see Dosage and Administration ( 2.7 )] .
…Physicians should be aware that CIALIS for once daily use provides continuous plasma tadalafil levels and should consider this when evaluating the potential for interactions with medications (e.g., nitrates, alpha-blockers, anti-hypertensives and potent inhibitors of CYP3A4) and with substantial consumption of alcohol [see Drug Interactions ( 7.1 , 7.2 , 7.3 )] .
The dose of CIALIS for use as needed should be limited to 10 mg no more than once every 72 hours in patients taking potent inhibitors of CYP3A4 such as ritonavir, ketoconazole, and itraconazole [see Drug Interactions ( 7.2 )] .
In patients taking potent inhibitors of CYP3A4 and CIALIS for once daily use, the maximum recommended dose is 2.5 mg [see Dosage and Administration ( 2.7 )] .
CYP3A4 inhibitors (e.g. ketoconazole, ritonavir) increase CIALIS exposure ( 2.7 , 5.10 , 7.2 ) requiring dose adjustment: CIALIS for use as needed: no more than 10 mg every 72 hours CIALIS for once daily use: dose not to exceed 2.5 mg CYP3A4 inducers (e.g. rifampin) decrease CIALIS exposure ( 7.2 ).
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.