Duration of erythema persists for 24-26 hours

• A. Minimal erythema
• B. Infrared radiation
• C. Ultraviolet radiation
• D. Second-degree erythema

Answer: (A)

In photodermatology testing, the mildest visible redness that appears after UV exposure and lasts about a day is the minimal erythema response. This pattern—redness that shows up roughly within 8–24 hours and persists for about 24 hours before fading—fits the described duration of 24–26 hours. It reflects the lowest UV dose that causes a perceptible, transient reddening of the skin, used to gauge an individual’s sensitivity and to set therapeutic UV doses.

Infrared radiation causes redness from heat but isn’t defined by a fixed 24-hour persistence like this. Ultraviolet radiation can produce erythema at various intensities and durations, but the specific, mild, transient red reaction described aligns with minimal erythema rather than a heavier burn or a deeper tissue damage. Second-degree erythema would indicate a more severe burn with longer healing and potential blisters, not just a one-day redness.