What Is Zinc Toxicity?

The NIH Office of Dietary Supplements says getting excessive amounts of zinc can cause nausea, dizziness, headaches, gastric distress, vomiting and loss of appetite, and that doses of 50 mg or more over a period of weeks can inhibit copper absorption, reduce immune function and lower HDL cholesterol, although it is unlikely a person would get that much zinc from food alone. It says the Tolerable Upper Intake Level for zinc is 40 mg for adults. ATSDR says harmful effects generally begin at levels 10 to 15 times higher than the amount needed for good health, that large doses taken by mouth even for a short time can cause stomach cramps, nausea and vomiting, and that taken longer, zinc can cause anemia and lower levels of good cholesterol.

The NIH Office of Dietary Supplements says using zinc-containing denture cream as directed, 0.5 to 1.5 grams a day, is not a concern, but that chronic, excessive use can lead to zinc toxicity, which can cause copper deficiency and neurologic diseases. In a February 2011 notice to all denture adhesive manufacturers, the FDA said it had received numerous reports of adverse events related to denture adhesives, that research suggests zinc in some of them may be a contributing factor, and that reported symptoms consistent with zinc toxicity included nerve damage in the limbs and blood disorders. The NIH National Center for Complementary and Integrative Health says using zinc in the nose can cause loss of the sense of smell that may be long-lasting or permanent, and that in 2009 the FDA warned consumers to stop using several intranasal zinc cold remedies linked to cases of lost smell.

Zinc fumes are a workplace hazard. NIOSH documentation says the most prevalent toxic effect of zinc oxide fume is metal fume fever, with symptoms including chills, fever, muscle pain, nausea and vomiting.