Which of the following is a contraindication for chemical exfoliation?

Allergies or sensitivities to products or ingredients are significant contraindications for chemical exfoliation because these conditions can lead to adverse reactions during or after the treatment. Chemical exfoliation involves the application of acidic products that can cause irritation or an allergic response in individuals who have known sensitivities. If a client has a history of allergic reactions to specific ingredients, performing a chemical exfoliation could exacerbate those reactions, leading to redness, swelling, or other adverse effects.

The other options do not inherently pose risks that would preclude chemical exfoliation. Recent use of sunscreen does not interfere with the efficacy of the treatment; routine facials typically do not create complications that would contraindicate an exfoliation; and using non-exfoliating skincare products does not present any issue that would prevent someone from safely undergoing a chemical exfoliation. Thus, being mindful of allergies or sensitivities is critical to ensuring the safety and effectiveness of the treatment.