Livedo reticularis appears as a reddish-blue, net-like pattern on the skin, most often on the legs, arms, or trunk. In many people, especially children, young adults, and those with fair skin, it is simply a temporary reaction to cold. Blood flow slows in the tiny vessels near the surface, deoxygenated blood pools, and a mottled pattern emerges, fading again as the skin warms. This primary form is usually harmless and needs nothing more than warmth and reassurance.

The story changes when the pattern persists, worsens, or comes with other symptoms. Pain, numbness, ulcers, headaches, fatigue, or joint pain can signal secondary livedo reticularis, linked to autoimmune disease, vasculitis, blood clotting disorders, or rare syndromes that raise stroke risk. In these cases, the skin becomes an urgent clue. Proper evaluation—examination, blood tests, sometimes biopsy or imaging—can uncover hidden illness, guide treatment with medications and lifestyle changes, and, in some cases, prevent life‑threatening complications.