Mottled skin discoloration: what it looks like and why it happens

Have you noticed a lace-like, blotchy pattern on your legs, arms, or trunk? That patchy purplish or reddish net-like look is often called mottled skin or livedo reticularis. Sometimes it’s harmless and shows up when you’re cold. Other times it’s a clue to circulation problems, inflammation, or a more serious condition. Knowing the likely causes and what to do next makes a big difference.

Common causes you can spot at home

Cold exposure is the easiest to recognize. Your skin can go mottled when small blood vessels constrict; warming up usually clears it within minutes to hours. Raynaud’s and vasospasm cause similar changes, often tied to cold or stress. Smoking and certain medications that narrow blood vessels can make mottling worse.

Other causes include poor circulation from peripheral artery disease, blood clots, or heart problems. Autoimmune conditions such as lupus or vasculitis can create a persistent reticular pattern. In very sick people, mottled skin can signal low blood flow or sepsis — that needs urgent care.

What you can do now, and when to see a doctor

Start simple: keep the area warm, stop smoking, and avoid tight clothing that restricts blood flow. Gentle leg movement and walking improve circulation if the mottling appears on the lower limbs. Moisturize if the skin is dry. If a medication change could be the cause, talk with your prescriber before stopping anything.

See a doctor if the discoloration is new and doesn’t fade with warming, or if you have pain, skin ulcers, numbness, fever, chest pain, fainting, or sudden limb coldness. Also get checked if the pattern appears with swelling or one-sided leg pain — these signs can point to blood clots or infection.

At the clinic you can expect a basic exam and some tests tailored to likely causes: blood work (CBC, markers of inflammation, clotting tests), Doppler ultrasound for blood flow, and sometimes autoimmune screens or a skin biopsy. Treatment targets the cause: warming and conservative care for benign cases; blood thinners for clots; antibiotics for infection; or immune therapies for autoimmune disease. Your doctor will explain the safest option for you.

In short: short-lived mottling after cold is usually harmless. Persistent, painful, spreading, or system-wide mottling deserves prompt medical attention. If you’re unsure, a quick call to your primary care provider or a clinic can help decide the next step.