Omeprazole is associated with the highest risk of drug-drug interactions among proton pump inhibitors due to its strong affinity for the cytochrome P450 (CYP) enzyme system (particularly CYP2C19 and CYP3A4), which play a crucial role in drug metabolism. By competitively inhibiting these enzymes, omeprazole can alter the metabolism of co-administered drug that are substrates of CYP enzymes, leading to significant pharmacokinetic interactions. These interactions can result in reduced drug efficacy or increased toxicity.

Although lansoprazole can cause drug-drug interactions, its potential for such interactions is lower than that of omeprazole. Rabeprazole and pantoprazole have the weakest potential for drug-drug interactions among the medications listed.

Learn more about proton pump inhibitors.

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Any views expressed above are the author’s own and do not necessarily reflect the views of WebMD or Medscape.

Cite this: Mary L. Windle. Rapid Rx Quiz: Dangerous Drug Interactions – Medscape – May 16, 2025.