Evidence

Research on oral zinc for specific conditions shows:

• Zinc deficiency. People who have low levels of zinc appear to benefit most from zinc supplements. This kind of deficiency isn't common in the United States.
• Colds. Evidence suggests that if zinc lozenges or syrup is taken within 24 hours after cold symptoms start, the supplement can help shorten the length of colds. However, use of intranasal zinc has been linked with the loss of the sense of smell, in some cases long term or permanently.
• Wound healing. People with skin ulcers and low levels of zinc might benefit from oral zinc supplements.
• Diarrhea. Oral zinc supplements can reduce the symptoms of diarrhea in children with low levels of zinc, such as from malnutrition. There isn't enough evidence to recommend use of oral zinc for children with diarrhea who have a healthy, varied diet.
• Age-related macular degeneration. Research suggests that oral zinc might slow the progression of this eye disease.

Zinc that's used topically is known as zinc oxide. Zinc oxide cream, ointment or paste is applied to the skin to prevent conditions such as diaper rash and sunburn.