Tolvaptan Is a Prescription Medication That Helps Your Body Remove Excess Water

Tolvaptan is a vasopressin V2-receptor antagonist — a type of medication that blocks a hormone signal telling your kidneys to hold onto water, helping your body excrete excess fluid without losing important electrolytes like sodium and potassium.

If your doctor has mentioned Tolvaptan, or you've seen the brand names Samsca or Jynarque on your prescription, this guide covers everything you need to know: what it's for, how to take it, what it costs, and the key safety information for 2026.

What Is Tolvaptan?

Here are the essential facts:

• Generic name: Tolvaptan
• Brand names: Samsca, Jynarque
• Drug class: Vasopressin V2-receptor antagonist (also called a "vaptan")
• Manufacturer: Otsuka Pharmaceutical
• FDA-approved: Samsca was approved for hyponatremia; Jynarque was approved for ADPKD
• Controlled substance: No — Tolvaptan is not a scheduled medication
• Generic available: No — there is no FDA-approved generic version as of 2026

For a deeper dive into how the drug works at a molecular level, check out our article on Tolvaptan's mechanism of action explained in plain English.

What Is Tolvaptan Used For?

FDA-Approved Uses

Samsca is approved for:

• Clinically significant hypervolemic and euvolemic hyponatremia — that is, dangerously low sodium levels in patients who have too much body water. This includes patients with heart failure and SIADH (syndrome of inappropriate antidiuretic hormone secretion).

Jynarque is approved for:

• Slowing kidney function decline in adults at risk of rapidly progressing autosomal dominant polycystic kidney disease (ADPKD) — a genetic condition where fluid-filled cysts grow in the kidneys over time.

Off-Label Uses

Some doctors also prescribe Tolvaptan off-label for:

• Heart failure with fluid overload (when other diuretics aren't enough)
• Cirrhosis-related hyponatremia
• Broader use in SIADH beyond the specific labeled indication

How Is Tolvaptan Taken?

Tolvaptan comes as oral tablets in several strengths:

• Samsca: 15 mg and 30 mg tablets
• Jynarque: 15 mg, 30 mg, 45 mg, 60 mg, and 90 mg tablets

Samsca Dosing

The typical starting dose is 15 mg once daily, which may be increased to 30 mg once daily after at least 24 hours based on sodium response. Samsca must be started in a hospital where your sodium levels can be monitored closely.

Jynarque Dosing

Jynarque uses a split-dose regimen — you take a larger dose in the morning and a smaller dose in the evening:

• Starting dose: 45 mg in the morning / 15 mg in the evening
• Can be titrated up to: 90 mg in the morning / 30 mg in the evening

Both formulations can be taken with or without food. With Jynarque, you must drink plenty of water — whenever you're thirsty and at bedtime — to avoid dehydration.

Who Should Not Take Tolvaptan?

Tolvaptan is not appropriate for everyone. You should not take it if you:

• Cannot sense or respond to thirst (this includes some elderly patients and infants)
• Have hypovolemic hyponatremia (low sodium caused by fluid loss, not excess)
• Are taking strong CYP3A4 inhibitors like Ketoconazole, Itraconazole, Clarithromycin, or Ritonavir
• Have anuria (your kidneys aren't producing urine)
• Have an uncorrected urinary outflow obstruction

Additionally, Samsca should not be used for more than 30 days in patients with underlying liver disease. Jynarque requires REMS enrollment and ongoing liver monitoring due to the risk of serious liver injury.

How Much Does Tolvaptan Cost?

Tolvaptan is one of the more expensive prescription medications on the market:

• Samsca (30-day supply): approximately $7,000–$10,000
• Jynarque (30-day supply): approximately $12,000–$18,000

There is no generic available in the US as of 2026, which keeps prices high.

How to Reduce Your Cost

• Insurance — Most commercial plans and Medicare Part D cover Tolvaptan with prior authorization. Expect specialty tier copays.
• Manufacturer savings — Otsuka offers copay assistance programs that can lower your cost to as little as $0–$10 per month for eligible commercially insured patients.
• Patient assistance — The Otsuka Patient Assistance Foundation provides free medication to qualifying uninsured or underinsured patients.

For a complete breakdown of savings options, read our guide to saving money on Tolvaptan.

Final Thoughts

Tolvaptan is a specialized medication that plays a critical role for patients with hyponatremia and ADPKD. It's not available as a generic, it requires close medical monitoring, and it's expensive — but manufacturer programs and insurance coverage can make it accessible. If you're having trouble finding Tolvaptan at a pharmacy, Medfinder can help you locate it quickly. And if you're exploring whether this medication is right for you, talk to a specialist who prescribes Tolvaptan about your options.