In the short term, consuming zinc in excess of the recommended upper limit (40 mg/day)[1] can result in gastrointestinal symptoms (e.g., abdominal pain, nausea, vomiting, diarrhea).[1][2] In the long term, excessive zinc intake has been associated with copper deficiency and iron deficiency, as well as suppression of the immune system.[3][4][5] Also, the application of intranasal zinc has been reported to cause a loss of smell in some people.[6]
What are zinc’s main drawbacks?
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•Last Updated: May 16, 2025
Zinc's main drawbacks include gastrointestinal symptoms from short-term excessive intake, long-term risks of copper and iron deficiency, immune system suppression, and potential loss of smell from intranasal application. The recommended upper limit for zinc consumption is 40 mg per day.