Central venous catheters (CVCs) may be used for treatment of critically and chronically unwell patients in hospital or in their homes. Complications can occur and should be resolved promptly so they do not result in increased lengths in hospital stay or readmission for patients receiving intravenous therapy at home. This article defines CVCs and the types of central venous access device that are in use in the U.K.; describes how to prevent occlusion and maintain the patency of CVCs; describes the types of occlusions that may occur; and discusses how to assess each type of occlusion and how they may be managed.