When taken in supplement form at doses of less than 40 mg daily, zinc is unlikely to cause negative or harmful side effects.
However, daily zinc supplementation at moderate or high doses over longer periods has been associated with low copper status, reduced immune function, and altered iron function (1).
Signs of excess zinc intake may include decreased appetite, nausea or vomiting, headaches, upset stomach, and diarrhea. This can occur in either an acute or chronic time frame depending on the dosage (1).
Zinc is found in foods such as beans, nuts, fortified cereals, grains, and dairy products (1).
It's important to consult a qualified health professional to assess your overall diet quality before starting zinc supplementation.