Blood Circulation: What Is Raynaud’s Phenomenon?

Raynaud’s phenomenon: Not just poor circulation

When you’re exposed to a cold environment, your body reacts by trying to preserve your core temperature. Blood vessels near the surface of your skin constrict, redirecting blood flow deeper into the body. If you have Raynaud’s phenomenon, this process is more extreme, and even slight changes in air temperature can trigger an episode, says rheumatologist Dr. Robert H. Shmerling, senior faculty editor at Harvard Health Publishing and corresponding faculty in medicine at Harvard Medical School.

“Cold weather is the classic trigger for Raynaud’s phenomenon. But it can occur any time of year — for example, when you come out of a heated pool, walk into an air-conditioned building, or reach into the freezer section at the supermarket,” he says. In addition to the hands, Raynaud’s can also affect the feet and, less often, the nose, lips, and ears. During an episode, the small arteries supplying the fingers and toes contract spasmodically, hampering the flow of oxygen-rich blood to the skin. Some of these vessels even temporarily collapse, and the skin becomes pale and cool, sometimes blanching to a stark white color.