Tab: Herbal medicines & food supplements. Syr: Zn: Decreased absorption of certain antibiotics eg, quinolones (ciprofloxacin, levofloxacin, ofloxacin) & tetracyclines (doxycycline, tetracycline); bisphosphonate (alendronate, etidronate, risedronate). Additive effects w/ cholesterol medicines. Inhibits absorption of copper & Fe. Reduced absorption of penicillamine. Reduced absorption w/ caffeine or tea, high levels of phosphorus, Ca, phytates (eg, bran, brown bread) or folic acid.