Zinc is usually safe for most adults when applied to the skin, or taken as zinc supplements by mouth. In some people, the routine use of zinc supplements can have negative side effects like nausea, vomiting, diarrhoea, metallic taste, kidney and stomach damage, and others. For this reason, routine use of zinc supplements is not recommended unless your healthcare professional has advised you otherwise. Consider the following special precautions before taking zinc and always consult your healthcare expert when starting on a new supplement.
- Using zinc on broken skin may cause burning, stinging, itching, and tingling.
- The use of zinc in high amounts is likely unsafe. Doses over the recommended amount may have adverse side effects like fever, coughing, stomach pain, fatigue, and others.
- Taking more than 100 mg of zinc supplements daily, or the use of zinc supplements for 10 years or more, may double the risk of prostate cancer. Additional research suggests that taking large amounts of multivitamins plus a separate zinc supplement may increase the possibility of dying from prostate cancer.
- Using more than 450 mg or more of zinc supplements daily can cause problems with blood iron. Even single doses of 10-30 grams of zinc can be fatal.
- Avoid the use of zinc nose sprays like Zicam and Cold-Eeze as these are possibly unsafe. Nasal sprays that contain zinc may cause the loss of ability to smell in more extreme cases. In June 2009, the US Food and Drug Administration (FDA) advised consumers to not use nose sprays that contained zinc after receiving over 100 reports of loss of smell.
- Use of zinc if you have HIV (human immunodeficiency virus/AIDS might shorten your life.
Pregnancy and breastfeeding
Use of zinc during pregnancy and breastfeeding is generally safe as long as it is used in the recommended daily amounts (RDA).
- Pregnant women over 18 should not take more than 40 mg of zinc per day.
- Pregnant women age 14 to 18 should not take more than 34 mg of zinc per day.
- Breastfeeding women over 18 should not take more than 40 mg of zinc per day.
- Breastfeeding women age 14 to 18 should not take more than 34 mg per day.