Intense pulsed light, or IPL, sends brief flashes of broad-spectrum light into the skin. Brown pigment and the small red vessels near the surface absorb that light as heat, which is why one treatment can address both sun spots and redness. Your clinician reviews your skin first and decides whether IPL is a sound choice for you.
IPL devices are FDA-cleared through the 510(k) pathway, which is a different route from FDA approval, and each device is cleared for its own list of uses. Those uses typically include benign pigmented lesions, such as freckles and sun spots, and benign vascular lesions, such as small surface vessels and the redness of rosacea. Your clinician will tell you plainly which of your concerns fall inside those uses and which do not.
The course of a treated spot is part of the process. It typically darkens after the visit, then flakes away over the following days, leaving more even skin beneath. Results build across a series of sessions rather than in one, and because the light is absorbed by pigment, sun exposure between visits works against you.
Device clearance and approval apply to particular products and uses. Ask which device or formulation will be used for your treatment.