This (painless) disorder is seen mainly in women, and is caused by the constriction of the small blood vessels in the skin. This results in poor circulation in the hands and feet, causing them to turn blue and become cold and sweaty. Localised swelling may also occur. Cold temperatures can exacerbate symptoms, while warmth can relieve them.  

Treatment involves keeping the foot warm so that blood can circulate normally. Wearing insulated boots, or liner socks may help to maintain normal skin temperature. The disorder itself cannot be cured, but it rarely worsens over time.