Zinc is a trace mineral needed by the human body in tiny amounts in order to maintain good health. In addition to preventing zinc deficiency, many people take zinc supplements for a variety of reasons, including boosting the immune system and preventing heart disease. Although zinc is generally safe and well-tolerated, large doses of zinc may cause a variety of side effects, including dizziness.
Ingesting large doses of zinc can lead to a condition known zinc toxicity. Symptoms of acute zinc toxicity can begin as rapidly as 30 minutes after consuming a high dose of zinc. Frequent symptoms of zinc toxicity include dizziness, headache and drowsiness, explains the University of Maryland Medical Center.
The maximum amount of zinc you should take in one day is 40 mg, according to the Office of Dietary Supplements of the National Institutes of Health. Ingesting more than 40 mg per day increases of risk of zinc toxicity and symptoms such as dizziness. Do not take more than 40 mg of zinc per day unless specifically instructed to do so by a qualified health practitioner.
The exact reason why excess zinc intake causes dizziness is not well understood, especially for cases of acute zinc toxicity caused by ingestion of one large dose of zinc. Chronic zinc toxicity, caused by long-term exposure to high levels of zinc, is known to lead to a deficiency in copper, which in turn can cause anemia, explains an article published in the February 1990 issue of the "American Journal of Clinical Nutrition." One common symptom of anemia is dizziness.
Acute zinc toxicity may cause additional symptoms, especially nausea and vomiting, as well as a metallic taste in the mouth, loss of muscle coordination, increased sweating and hallucinations. Chronic zinc toxicity has been reported to result in a weakened immune system, as well as potentially harmful alterations in the ratio of HDL, or "good cholesterol" to LDL, or "bad cholesterol."