Desmopressin (DDAVP) is an synthetic derivative of vasopressin that acts to decrease urine formation by increasing water reabsorption in the kidneys. By decreasing urine formation, it leads to plasma volume expansion. In a placebo controlled trial, we showed that DDAVP decreased standing heart rate, change in heart rate with standing, and improved symptoms.
Side effects associated with DDAVP include headaches, edema, and hyponatremia (low salt concentration in the blood). Because patients with POTS are encouraged to drink copious amounts of water and DDAVP causes free water retention it is theoretically possible that regular use in POTS could lead to severe hyponatremia. Caution should be exercised in using DDAVP regularly without data from long term studies that evaluate the side effects associated with regular use. We do have several patients who use DDAVP for special events, with instructions to take no more than one dose per week.