VIT C, CITRIC ACID INCREASE ITS ABSORPTION. ANTACIDS, ZINC AND MINERAL SUPPLIMENTS, BICARBONATES, CARBONATES, OXLATES, PHOSPHATES MAY IMPAIR ITS ABSORPTION. ABSORPTION OF FLUOROQUINOLONES, LEVODOPA, METHYLDOPA, PENICILLAMINE, TETRACYCLINE IS DECREASED. IT REDUCES THE EFFICACY OF THYROXIN.