When taken with blood thinning (anticoagulant) medicines (e.g., warfarin, dicumarol) or together with thrombolytic agents (e.g., streptokinase), ibuprofen may cause stomach and intestinal bleeding.
Aspirin decreases the amount of ibuprofen in the blood while salicylates and other NSAIDs (e.g., mefenamic acid, naproxen, diclofenac, ketoprofen, etc.) increase the risk of stomach and intestinal bleeding in patients receiving ibuprofen.
Ibuprofen increases the amount of lithium in the blood (increased risk toxicity) probably by reducing excretion of lithium.
Ibuprofen may cause acute reduction in kidney function and blood pressure response to ACE inhibitors (e.g., captopril, enalapril, ramipril, imidapril, fosinopril, lisinopril).
Ibuprofen may reduce the effect of diuretics such as furosemide and thiazide.