Updated: January 25, 2026
What Is Jantoven? Uses, Dosage, and What You Need to Know in 2026
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Overview
What is Jantoven? Learn about warfarin's uses, dosages, how it works, and important safety information every patient should know in 2026.
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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.
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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.
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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
Real-time availability
Is Jantoven in stock near you?
Verified 2h ago
Based on 50 real pharmacy checks · 2 patients helped
Jantoven is in a shortage right now — Medfinder calls pharmacies near you to track down the ones that have it.
As of August 9, 2026, 8:00 PM ET, Jantoven is currently experiencing a shortage. Across 50 pharmacy checks Medfinder placed in the last 30 days, Jantoven was confirmed in stock 2% of the time.
- Pharmacy checks
- 50
- FDA status
- Not listed
- Updated
- 2h ago
Jantoven is not on the FDA's active shortage list. Medfinder's own pharmacy calls put real-time availability at 2% across 50 checks in the last 30 days. Availability varies by metro, with the most pharmacy activity recorded around Waltham, MA. These numbers are recomputed continuously from live pharmacy calls, so this page reflects current conditions rather than a static estimate.
Jantoven availability questions
Is Jantoven in stock right now?
As of August 9, 2026, 8:00 PM ET, Jantoven was confirmed in stock at 2% of 50 pharmacies Medfinder checked in the last 30 days. Availability changes daily, so we re-check in real time when you search.
How does Medfinder help me find Jantoven?
Medfinder calls pharmacies in your area to verify whether Jantoven and your specific dose are in stock, then sends you the pharmacy name, address, and phone number.
Need Jantoven? We'll find the pharmacy that has it.
Sources: FDA Drug Shortages + Medfinder pharmacy data · Methodology · Full Jantoven data
Frequently Asked Questions
Jantoven (warfarin sodium) is used to treat and prevent blood clots, including deep vein thrombosis (DVT), pulmonary embolism (PE), stroke prevention in atrial fibrillation, clot prevention with mechanical heart valves, and reducing thromboembolic risk after a heart attack. It is also used prophylactically after hip and knee replacement surgery.
Duration depends on your condition. Some patients take Jantoven for a defined period (e.g., 3–6 months after a DVT/PE), while others take it for life (e.g., AFib, mechanical heart valves, recurrent VTE). Your prescriber will determine the appropriate duration based on your diagnosis and risk factors.
You don't need to avoid specific foods, but you need to maintain a consistent intake of vitamin K. Vitamin K is found in leafy greens (spinach, kale, broccoli, Brussels sprouts). Sudden large increases in vitamin K will lower your INR; sudden decreases will raise it. Eat these foods regularly in consistent amounts and avoid dramatic dietary changes.
Yes. Jantoven and Coumadin are both brand-name warfarin sodium tablets containing the same active ingredient. Coumadin is the older brand (no longer actively marketed by its original manufacturer), while Jantoven is made by Upsher-Smith Laboratories. Both are bioequivalent to generic warfarin.
An INR significantly above your target range (generally above 4.0) means your blood is taking too long to clot and increases your bleeding risk. Contact your prescriber immediately. Depending on how high your INR is and whether you're bleeding, your provider may instruct you to skip a dose, take vitamin K, or seek emergency care for immediate reversal.
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