Sequelae after the intravenous injection of three benzodiazepines--diazepam, lorazepam, and flunitrazepam

The occurrence of thrombosis and phlebitis after intravenous injection of 10 mg diazepam, 4 mg lorazepam, or 1-2 mg flunitrazepam was studied on the second or third and the seventh to 10th days. A significantly higher incidence occurred with all drugs on days 7 to 10 than on days 2 and 3. Painless thrombosis occurred much more often with diazepam than with the other two benzodiazepines. Its incidence was greater in small hand or arm veins than in large antecubital vessels. Lorazepam and flunitrazepam therefore have clear advantages over diazepam.