Pentoxifylline works by increasing the supply of oxygen to the tissues. It does this by causing the blood vessels to widen, resulting in increased blood supply. It also has effects on the blood cells, which results in a thinning of the blood, allowing it to pass more easily through the blood vessels. Both these effects are useful in peripheral vascular disease, where the blood vessels in the extremities are narrowed. This medicine reduces the pain of peripheral vascular disease by increasing the blood flow and delivery of oxygen to the tissues.