In more than 1,500 intravenous administrations of diazepam (Valium) for gastrointestinal endoscopy, an incidence of thrombophlebitis of approximately 3.5% resulted. In a few cases, the phlebitis was protracted and involved a long segment of vein. We now recommend that small veins or hand veins be avoided. If the vein is painful after injection, vigorous flushing of the vein is indicated. Administration of heparin sodium for two to three days is effective, and this therapy should be considered in more severe cases. Preliminary results of a randomized prophylactic-flush study indicate decreased severity with flushing.
Langdon DE, Harlan JR, Bailey RL. Thrombophlebitis With Diazepam Used Intravenously. JAMA. 1973;223(2):184-185. doi:10.1001/jama.1973.03220020050018