<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (July 2007) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (July 2007) (Learn how and when to remove this template message) </Td> </Tr> <P> Collapsed veins are a common result of chronic use of intravenous injections . They are particularly common where injecting conditions are less than ideal, such as in the context of drug abuse . </P> <P> Veins may become temporarily blocked if the internal lining of the vein swells in response to repeated injury or irritation . This may be caused by the needle, the substance injected, or donating plasma . Once the swelling subsides, the circulation will often become re-established . </P>

How can you tell if you have a collapsed vein