Safety and side effects

Zinc supplements taken by mouth may cause:

• Diarrhea.
• Dizziness.
• Headache.
• Nausea.
• Upset stomach.
• Vomiting.

Taking zinc supplements by mouth long-term and in high doses can lead to copper deficiency. People with low copper levels might have brain and nervous system issues. Those issues may include numbness and weakness in the arms and legs.

According to the National Institutes of Health, 40 mg of zinc a day is the upper limit of a daily dose of zinc taken by mouth for all people age 19 and older. For people 18 and younger, the upper daily limit of zinc varies depending on age. If you have questions about how much zinc a child needs, talk with a healthcare professional.

Don't use zinc that's placed in the nose, called intranasal zinc. This form of zinc has been linked to loss of the sense of smell.