Phlebitis is inflammation of the veins, which can be superficial (affecting surface veins) or deep (affecting deeper veins). Thrombophlebitis occurs when a blood clot forms in an inflamed vein, causing pain and potentially blocking blood flow. Superficial phlebitis usually resolves quickly with proper care but can sometimes lead to deep vein thrombophlebitis, a more serious condition. Deep vein thrombophlebitis carries the risk of pulmonary embolism if clots break off and travel to the lungs. Treatment depends on the severity and location of the phlebitis but may include elevation, compression, medications, and occasionally surgery.