When certain medicines are taken with Cozaar, drug interactions may occur and sometimes result in side effects or complications. For example, your body may metabolize the drugs differently than intended and significantly increase or decrease the drug levels in your system. Medicines that can potentially cause Cozaar interactions include: potassium-sparing diuretics, nonsteroidal anti-inflammatory drugs, rifampin, and potassium supplements or salt substitutes with potassium.