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.
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.