Products
This domain tests ingredient knowledge, product selection by skin type and condition, and safe use with medications and other services.
Ingredient categories
- Humectants (glycerin, hyaluronic acid) attract water; emollients (plant oils, shea butter) soften; occlusives (petrolatum, dimethicone) reduce water loss.
- Exfoliants: AHAs such as glycolic and lactic acid, BHAs such as salicylic acid, and physical scrubs. AHAs work best around pH 3–4; pH matters for efficacy and irritation.
- Retinoids increase cell turnover and cause photosensitivity. Antioxidants such as vitamin C protect against free radicals; daily SPF 30 or higher is standard.
Selection and safety
Assess skin type, Fitzpatrick phototype, allergies, medications and pregnancy status. Avoid retinoids and high-dose salicylic acid in pregnancy. Patch test tinted products and known allergens 24–48 hours ahead. Respect the period-after-opening symbol, never decant into unlabeled containers, and discard expired product. Dilute essential oils typically to 1–3% for body use and avoid photosensitizing citrus oils before sun exposure.
Worked example: a client using topical tretinoin nightly requests a deep-cleansing facial with a glycolic peel and eyebrow wax. Reasoning: tretinoin thins the stratum corneum, so AHA and waxing raise the risk of irritation and skin lifting. Best action: skip the peel, do gentle cleansing and hydration, avoid aggressive extraction, and defer waxing per manufacturer guidance (commonly about seven days off the retinoid). Document the advice.
Traps
Assuming "natural" means safe, over-exfoliating, waxing retinoid-treated skin, mixing acids without checking pH, and ignoring the period-after-opening date.