What are the potential side effects of zinc supplementation?

From the Guidelines

Zinc supplementation can cause several side effects, particularly when taken in high doses or for extended periods, including headaches, nausea, vomiting, decreased appetite, diarrhea, and abdominal cramps, as well as more severe adverse effects such as low copper, anemia, leukopenia, neutropenia, and gastrointestinal ulcers with prolonged use.

Potential Side Effects

The potential side effects of zinc supplementation are numerous and can be severe. Common side effects include:

• Nausea
• Vomiting
• Decreased appetite
• Diarrhea
• Abdominal cramps High doses of zinc, exceeding 40mg daily, can interfere with copper absorption, potentially leading to copper deficiency anemia 1. Long-term high-dose supplementation may also impair immune function.

Recommended Dietary Allowance

The typical recommended dietary allowance for zinc is 11mg daily for adult men and 8mg for adult women, with slightly higher amounts during pregnancy and lactation (11-12mg) 1.

Minimizing Side Effects

To minimize side effects, zinc supplements should be taken with food, and doses should not exceed the upper limit unless prescribed by a healthcare provider. Different forms of zinc supplements may cause varying degrees of gastrointestinal discomfort, with some forms typically causing more stomach irritation than others. According to a recent study, oral zinc has been associated with headaches, nausea, vomiting, decreased appetite, diarrhea, and abdominal cramps, and in high doses with prolonged use, oral zinc can have more severe adverse effects such as low copper, anemia, leukopenia, neutropenia, and gastrointestinal ulcers 1.

From the FDA Drug Label

Ask a doctor or pharmacist before use if you are taking minocycline, doxycycline, tetracycline, or are on coumadin therapy; zinc treatment may inhibit the absorption of these medicines. Warnings Ask a doctor before use if you have a sensitivity to zinc or are allergic to zinc or any of the other ingredients in this product.

The potential side effects of zinc supplementation include:

• Allergic reactions to zinc or other ingredients in the product 2
• Interactions with other medicines, such as minocycline, doxycycline, tetracycline, or coumadin therapy, which may have their absorption inhibited by zinc treatment 2
• Sensitivity to zinc 2

Note that these are not exhaustive lists of side effects, but rather specific examples mentioned in the drug labels.

From the Research

Potential Side Effects of Zinc Supplementation

The potential side effects of zinc supplementation can be categorized into several areas, including:

• Gastrointestinal symptoms:
  • Nausea 3, 4, 5
  • Vomiting 3, 4, 5
  • Epigastric pain 3
  • Abdominal cramps 5
  • Gastric irritation 5
• Other symptoms:
  • Lethargy 3
  • Fatigue 3
  • Headaches 5
  • Loss of appetite 5
• Effects on nutrient levels:
  • Induced copper deficiency 3, 6
  • Impaired iron utilization 3
  • Adverse effects on HDL cholesterol concentrations 3
  • Adverse effects on the ratio of low-density-lipoprotein to high-density-lipoprotein (LDL/HDL) cholesterol 3
• Increased risk of zinc toxicity:
  • High intakes of zinc relative to copper can cause copper deficiency 6
  • Excessive consumption of zinc supplements can lead to chronic zinc toxicity 6