Concurrent administration of antacids with oral iron may decrease iron absorption. When taken concomitantly, absorption of both iron salts and tetracyclines is diminished. Responses to iron may be delayed when receiving concomitant chloramphenicol therapy. Iron salts have also been reported to decrease absorption and thus reduce the bioavailability and clinical effect of levodopa with carbidopa, methyldopa, penicillamine, and some quinolones (ciprofloxacin, norfloxacin, ofloxacin). Oral iron preparations should not be ingested concomitantly with or within 2 hrs of a dose of these medications.
Concurrent administration of chloramphenicol and folic acid in folate-deficient patients may result in the antagonism of the hematopoietic response to folic acid.