About 20% of adults faint recurrently. These patients are often highly symptomatic, have problems with employment and driving and have reduced quality of life. There are no therapies that have withstood the test of adequately designed and conducted randomized clinical trials. Midodrine is a prodrug whose metabolite is an alpha-1 adrenergic agonist that increases venous return to the heart and raises blood pressure. There is considerable lower level evidence that it might prevent vasovagal syncope.