Any person may develop an irritation or allergic response to any ingredient at any time, even if they have previously used the product or ingredient. Intolerance, sensitivity, or allergy to iS Clinical products is extremely uncommon. Allergic or sensitivity responses usually result from improper application of products, combining products that should not be used together, or using too many active products closely within the same regimen. iS Clinical products incorporate many botanical ingredients, and as different plants might share common characteristics, plants from different environments could contain some proteins that cross-react with others. Any individual with a previous, severe allergic response to a skin care product, ingredient, or plant should consult with their health care practitioner prior to beginning use of a new or additional skin care product.