Skin Analysis, Disorders, Diseases, and Contraindications
Analysis, not diagnosis
Assess under good light with magnification: oiliness, pore size, texture, hydration, pigmentation, vascularity, laxity, and Fitzpatrick type I–VI (UV response). Sort the skin into dry, oily, combination, normal, or sensitive. You describe what you see; you do not name a disease. That distinction is the single most tested idea in this domain.
Describing lesions
Primary: macule (flat color change), papule (raised, small), nodule (deeper, larger), pustule (pus-filled), vesicle (small blister), bulla (large blister), wheal (edema), cyst. Secondary: scale, crust, fissure, erosion, ulcer, scar, excoriation. Clear descriptive language protects you and the client.
Work versus refer
Within cosmetic scope: comedones, milia, dehydration, dull texture, mild uneven tone. Refer: anything new, changing, bleeding, or painful; suspected melanoma (ABCDE - asymmetry, border, color, diameter, evolving); pearly lesions with visible vessels; herpes simplex (cold sore - contagious, do not treat); impetigo; conjunctivitis; ringworm; warts; undiagnosed rashes.
Contraindications
Waxing and chemical exfoliation: isotretinoin (commonly six months; follow the prescriber), topical retinoids (stop several days), recent peels or laser, sunburn, varicose veins, thin crepey skin, keloid history, active infection, and caution with diabetes because healing is slower.
Traps
Being asked which condition to treat - the answer is refer. Also watch for a client who wants a mole 'just looked at.'
Rule of thumb
New, changing, bleeding, or painful? Refer. If in doubt, do the gentler service or none at all.