Combining bismuth subsalicylate with sulfinpyrazone (Anturane) or probenecid is not recommended because bismuth subsalicylate may suppress the therapeutic effects of both drugs. Tetracycline and quinolone antibiotics may form insoluble complexes with bismuth subsalicylate. While bismuth subsalicylate should be avoided in patients taking these antibiotics if possible, separating administration by 2 hours may be sufficient to avoid this interaction. Bismuth subsalicylate should be used cautiously in patients taking methotrexate (Trexall). Bismuth subsalicylate is broken down to salicylic acid which is known to increase blood levels of methotrexate. Patients especially at risk for this interaction include those on high-dose methotrexate therapy, elderly patients, and patients with reduced kidney function.