Inflammation of the wall of a vein, usually in the leg. Phlebitis is almost always associated with the formation of a blood clot at the point of inflammation. A distinction must be made between inflammation of superficial and deeper veins of the leg. In the case of a deeper vein it is principally symptomatic of a thrombosis; the term phlebitis is usually reserved for inflammation of veins nearer the surface. The most important causes are damage to the wall of a vein (by injections or infusion) and slowing of the bloodstream (in patients confined to bed). Phlebitis can gradually build up in varicose veins in particular. Bacteria are not involved in phlebitis; the inflammation is a reaction to irritation and damage. An inflamed vein is red, swollen and painful. Usually only a small section of the vein is affected, but the condition can spread throughout its length. Treatment is by rest for the leg and a wet bandage on the inflamed vein. Ointment to halt inflammation can also be used if necessary. Phlebitis is usually cured completely, but sometimes one or more valves in the vein can be permanently damaged by the condition, which can later cause or aggravate varicose veins.