Are there any concerns or considerations?

1. Use of zinc supplementation without medical guidance could lead to misdiagnosis

• Symptoms of a common cold (that may warrant the use of zinc) are often non-specific and overlap with illnesses that may require antibiotics (certain bacterial illnesses) or other medical investigation/intervention. This includes the need for isolation due to an infective illness (e.g., with influenza or COVID-19).
• The use of zinc supplementation should be under medical guidance and must not replace or interfere with other standard practices of illness assessment and management.

2. Different zinc preparations and dosing may cause confusion

• Multiple different preparations (zinc salts) and dosages used limit the comparability of studies to date.
• Doses are quoted as the elemental zinc dose, however the available dose may differ as some lozenges contain compounds that more tightly bind zinc ions.¹
• The majority of research has been on zinc lozenges, but there is little direct comparison of zinc lozenges compared to tablets.

3. Side effects- largely mild but worth noting

• Bad taste, nausea and constipation have been reported following zinc supplementation.^1,6,8
• Copper deficiency has also been reported with long term high dose zinc supplementation, presumably because of competitive absorption within the gastrointestinal tract.⁴