Which statement about infrared heat lamp usage is true?

• A. It filters out harmful ultraviolet radiation
• B. Local metabolism is increased
• C. Erythemia is produced
• D. It emits radiation only ultraviolet rays

Answer: (B)

Raising tissue temperature increases local metabolism. When infrared rays heat the skin and underlying tissues, enzymatic activity speeds up and blood flow increases, delivering more oxygen and nutrients while helping to remove waste products. This boost in metabolic activity supports tissue repair and can reduce stiffness in the treated area, which is the primary therapeutic outcome of infrared heat therapy.

Some devices may filter UV light and heat can cause redness from vasodilation, but those effects are secondary. The defining, reliable effect of using an infrared heat lamp is the rise in local metabolism. Also, infrared lamps do not emit only ultraviolet rays; they deliver infrared radiation predominantly, with minimal UV exposure.