Rohypnol effects. Rohypnol is also called the date rape drug. Rohypnol can cause anterograde amnesia, loss of inhibition, sedation, confusion, urinary retention, GI upset & drop in blood pressure. When rohypnol is used with alcohol (or other drugs) there may be slurred speech, red eyes, poor judgment and decreased motor skills. There are reports of violent behavior on rohypnol.