What is a primary cause of an external effect on the skin?

• A. Misuse of products
• B. Genetics
• C. Diet
• D. Sun exposure

Answer: (A)

External effects on the skin commonly come from substances we put on it or environmental interactions with it. When products are used incorrectly—too often, in the wrong order, with ingredients that clash, or on skin that's already irritated—the skin barrier can be disrupted and become irritated or sensitized. That disruption shows up as redness, burning, flaking, or breakouts, which are direct external reactions caused by how the product is used. Genetics and diet shape skin health from within, and sun exposure is a well-known external factor, but in terms of direct, product-related external responses, misuse of products most clearly triggers those external effects.