Vasopressin: Uses, Mechanism, and Side Effects

Patients in vasodilatory shock often remain dangerously hypotensive even after fluids and standard pressor drugs. Vasopressin is a hormone-based injectable used in this exact clinical gap, to help raise blood pressure when other measures have not worked.

Key takeaways

• Vasopressin is approved to raise blood pressure in adults with vasodilatory shock who stay hypotensive despite fluids and catecholamines.
• It works by binding V1 receptors on blood vessels, triggering vasoconstriction, and V2 receptors, which affect water retention.
• More than 780 trials have registered on vasopressin or related compounds, reflecting decades of clinical study.
• FAERS reports linked to vasopressin most often describe drug ineffectiveness, hypotension, and complications of the underlying critical illness rather than a distinct side-effect profile.
• The approved label does not carry a boxed warning.

What Vasopressin Is

Vasopressin is a peptide hormone formulated as an injectable, marketed under the brand name Vasopressin. It causes blood vessels to constrict by binding V1 receptors on vascular smooth muscle, which activates a signaling pathway that releases calcium inside the cell. Separately, it acts on V2 receptors to promote water retention by the kidneys, the same antidiuretic effect the natural hormone provides in the body.

What Vasopressin Is Approved For

Vasopressin injection is indicated to increase blood pressure in adults with vasodilatory shock who remain hypotensive despite receiving fluids and catecholamine medications. This is a narrow, specific use in critically ill patients rather than a general blood pressure treatment. The label does not carry a boxed warning.

What The Evidence Shows

Vasopressin and closely related compounds appear in 788 registered clinical trials, spanning decades of investigation across shock, hormone deficiency, and cardiovascular research. Among sampled studies, one completed Phase 2 trial examined the aquaretic drug tolvaptan's effect on the nitric oxide system in a dose-response design. A separate Phase 1 trial, currently recruiting, is studying intranasal oxytocin in patients with arginine-vasopressin deficiency. A third study of unknown phase and status looked at copeptin, a related marker, for predicting infarct size and prognosis after ST-elevation myocardial infarction.

Reported Side Effects

FAERS report counts reflect associations, not confirmed incidence or direct causation. The most frequently reported terms involve treatment failure and the severity of the underlying condition: drug ineffective (1,333 reports), off label use (545), and hypotension (509). Other commonly reported terms include cardiogenic shock (418), multiple organ dysfunction syndrome (409), sepsis (404), condition aggravated (392), and toxicity to various agents (338). Because vasopressin is typically given to patients who are already critically ill, many of these reports likely reflect the severity of the underlying shock state rather than a drug-specific effect.