Thrombosis (clotting) in veins is divided into two classes, depending on whether or not the wall of the affected vein is inflamed. If it is inflamed the condition is called thrombophlebitis; if it is not, the condition is known as phlebothrombosis.

In thrombophlebitis, clotting in the vein follows inflammation of the wall of the vein. The affected vessel is red, tender, painful, and hard. The clot sticks to the wall of the vein and there is little danger of it breaking away and producing an embolus. Infection of the vein may be a complication of varicose veins, may be secondary to thromboangitis obliterans, or may have no obvious cause. Damage to the walls of varicose veins may be done intentionally by the injection of sclerosing medications in an effort to eliminate the various veins.

Treatment of thrombophlebitis is initial rest, analgesics, and support stockings. After the initial resting period, the person should start walking to improve the flow of blood through the veins.