Conivaptan vs Tolvaptan: Key Differences and What You Need to Know

When it comes to treating low sodium levels in the blood — a condition called hyponatremia, a medical condition where sodium levels in the blood fall below normal, often due to excess water retention or hormonal imbalances — two drugs stand out: Conivaptan, a vasopressin receptor antagonist given intravenously, primarily used in hospital settings for acute cases and Tolvaptan, an oral medication that works similarly but is designed for longer-term use in chronic conditions like SIADH or heart failure. Both block the action of vasopressin, the hormone that tells your kidneys to hold onto water. But how they’re used, who they help, and what risks they carry are very different.

Conivaptan is only given in a hospital, usually through an IV, because it works fast and needs close monitoring. It’s often used when someone’s sodium is dangerously low and needs a quick fix — like after surgery, in the ICU, or with severe syndrome of inappropriate antidiuretic hormone secretion (SIADH, a condition where the body makes too much vasopressin, causing water retention and low sodium). Tolvaptan, on the other hand, is taken as a pill. It’s meant for people with long-term low sodium, especially those with heart failure or liver disease. It doesn’t need constant IV access, but it requires regular blood tests to avoid overcorrecting sodium too quickly, which can cause brain damage.

Side effects differ too. Conivaptan can cause infusion site reactions, low blood pressure, and headaches. Tolvaptan’s biggest risk is liver damage — the FDA even put a black box warning on it. It also causes extreme thirst and frequent urination, which can be hard to manage at home. Neither drug is for everyone. Conivaptan is too intense for outpatient use. Tolvaptan’s liver risk makes it a last-resort option for many doctors.

What you’ll find in the posts below are real-world comparisons, patient experiences, and clinical insights on how these two drugs stack up. You’ll see how doctors choose between them, what labs to track, and which conditions respond best to each. No fluff. Just clear, practical info to help you understand when one makes more sense than the other — and why.