Cimetidine and Posaconazole Interaction

Understanding the Cimetidine and Posaconazole Interaction

FDA-approved prescribing information for these two drugs flags their combination as a major-severity interaction. Cimetidine belongs to the H2 Receptor Antagonist class and Posaconazole belongs to the Azole Antifungal class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Cimetidine changes the environment in the stomach, which can prevent the body from absorbing enough posaconazole into the bloodstream. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.

Context around a specific patient determines real-world impact. Cimetidine has 77 total documented interactions on file in this dataset, and Posaconazole has 27. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Avoid taking these two medicines together unless your doctor determines that the benefits are greater than the risks. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.

An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Cimetidine or Posaconazole based on a web page, speak with your prescriber or pharmacist before making any change.