Which statement about skin absorption is true?

• A. Oil-based products are absorbed more easily
• B. Water-based products are absorbed more easily
• C. Absorption is unaffected by skin condition
• D. The genital area is least absorptive

Answer: (A)

Oil-based formulations are absorbed more quickly because the skin’s outer layer is a lipid barrier. Lipophilic carriers in oil-based products merge with the stratum corneum’s lipid matrix, letting the active ingredient diffuse into the skin more readily. Water-based products don’t have that lipid affinity, so they tend to stay on the surface or require additional permeation aids to get through. The genital area is not least absorptive; in fact, certain areas can be more permeable due to thinner skin. Also, skin condition matters: damaged or irritated skin increases absorption, not leaves it unchanged.