What Is Jantoven? Uses, Dosage, and What You Need to Know in 2026

Jantoven is the brand name of warfarin sodium — one of the oldest and most prescribed blood thinners in the world. Despite being first approved by the FDA in 1954, warfarin remains a cornerstone of anticoagulation therapy for millions of Americans. Whether you're newly prescribed Jantoven or have been taking it for years, this complete guide answers the most important questions about what it is, what it does, and how to take it safely.

What Is Jantoven?

Jantoven is a brand-name oral anticoagulant (blood thinner) manufactured by Upsher-Smith Laboratories. Its active ingredient is

warfarin sodium, a vitamin K antagonist (VKA). It belongs to the drug class called coumarins and indandiones. Jantoven is identical in active ingredient to generic warfarin sodium and the brand Coumadin. It is available as color-coded tablets in strengths of 1 mg, 2 mg, 2.5 mg, 3 mg, 4 mg, 5 mg, 6 mg, 7.5 mg, and 10 mg.

What Is Jantoven Used For?

Jantoven is prescribed to treat and prevent blood clots. Specifically, it is FDA-approved for:

Deep vein thrombosis (DVT): Treatment and prevention of blood clots in the deep veins of the legs or arms

Pulmonary embolism (PE): Treatment and prevention of blood clots in the lungs

Atrial fibrillation (AFib): Prevention of stroke and systemic embolism in patients with irregular heart rhythm

Mechanical heart valves: Prevention of clot formation on prosthetic heart valves

Post-MI (heart attack): Reduction of risk of death, recurrent MI, and stroke after a heart attack

Surgical prophylaxis: Prevention of blood clots after orthopedic surgery such as hip or knee replacement

How Does Jantoven Work?

Warfarin works by blocking the activity of vitamin K in the liver. Vitamin K is essential for producing clotting factors II, VII, IX, and X, as well as proteins C and S. Without adequate clotting factors, blood takes longer to form clots — reducing the risk of dangerous clots forming in blood vessels or on heart valves. Jantoven does not dissolve existing clots but prevents them from growing larger or new ones from forming.

Jantoven Dosage: How It's Determined

Unlike most medications where everyone takes the same dose, Jantoven dosing is

highly individualized. Your provider determines your dose based on your INR (International Normalized Ratio) — a blood test that measures how long it takes your blood to clot. The target INR depends on your condition:

Most AFib, DVT, PE patients: target INR 2.0–3.0

Mechanical heart valve patients: target INR typically 2.5–3.5

Jantoven is taken

once daily at the same time each day, with or without food. Typical starting doses range from 2 to 5 mg per day. Your dose will be adjusted frequently in the first weeks until your INR stabilizes, then checked every 1–4 weeks long-term. INR results above 4.0 significantly increase bleeding risk without additional clot-prevention benefit.

Important Things to Know Before Taking Jantoven

Never skip a dose. If you miss a dose, take it as soon as you remember the same day. Never double up.

Keep your diet consistent. Vitamin K-rich foods (leafy greens, broccoli, kale) reduce warfarin's effect. You don't need to avoid them — just eat them in consistent amounts.

Tell all your providers you take warfarin. This includes dentists, surgeons, and emergency room staff, as procedures may need to be timed around your anticoagulation.

Avoid NSAIDs. Ibuprofen, naproxen, and aspirin (unless prescribed) increase bleeding risk. Use acetaminophen (Tylenol) at appropriate doses for pain relief.

Limit alcohol. Excessive alcohol raises your INR and increases bleeding risk.

Do not take during pregnancy unless absolutely required (e.g., mechanical heart valves). Warfarin can cause fetal harm.

Jantoven vs. Generic Warfarin vs. Coumadin

Jantoven and Coumadin are both brand-name versions of warfarin sodium; generic warfarin sodium tablets from other manufacturers contain the same active ingredient. The FDA requires all generic warfarin products to meet tighter bioequivalence standards due to the drug's narrow therapeutic index. While switching between formulations is generally safe with appropriate INR monitoring, many patients and providers prefer consistency on one formulation once INR is stabilized.

Finding Jantoven at Your Pharmacy

Because most pharmacies stock generic warfarin rather than brand-name Jantoven, finding the brand can sometimes require extra effort. Use medfinder to find pharmacies near you that have Jantoven in stock — the service calls pharmacies on your behalf and texts you which ones can fill your prescription. Also see our guide on

Jantoven side effects and when to call your doctor.