Compression socks use graduated pressure to improve blood flow in the legs. They're tightest at the ankle and loosen as they move up the leg. They help blood move up the legs and prevent it from pooling in the ankles, leading to swelling. They can also help prevent blood clots.
Therapeutic compression socks are usually prescribed by a physician, especially for people who are on their feet all day, who have varicose veins, who have just had surgery, who are going on a long flight or car ride, or who otherwise have circulation problems. They are considered durable medical equipment and may be covered by insurance under that benefit.
Visit a home health or medical equipment store so that leg measurements can be taken after compression socks are prescribed to ensure a good fit. When the socks are tight, a poor fit can actually cut off circulation rather than enhance it.
To care for the socks, wash them daily with mild soap and warm water. Allow them to air dry completely before wearing them again. If possible, get at least two sets. While one set is being washed and dried, wear the second set. Replace the socks every three to six months to maintain optimal support.