Warfarin Bleeding: Signs, Risks, and What to Do When It Happens

When you take warfarin, a blood thinner used to prevent clots in people with atrial fibrillation, artificial heart valves, or deep vein thrombosis. Also known as Coumadin, it saves lives—but it can also cause dangerous bleeding if not monitored closely. Warfarin bleeding isn’t rare. It’s one of the most common reasons people on blood thinners end up in the ER. And it doesn’t always look like a big cut or bruise. Sometimes it’s just a headache that won’t go away, or urine that turns dark.

What makes warfarin tricky is that it doesn’t have a built-in safety net. Unlike newer blood thinners, you can’t just take it and forget it. Your body’s response changes based on diet, other meds, even how much vitamin K you eat. That’s why your INR level, a blood test that measures how long it takes your blood to clot matters so much. If your INR is too high—above 4.5—you’re at serious risk. Bleeding can happen inside your skull, gut, or muscles without warning. A fall that used to give you a bruise might now cause internal bleeding. And if you’re on antibiotics, antifungals, or even St. John’s wort? That can spike your INR overnight.

Some people think if they feel fine, they’re safe. But warfarin bleeding doesn’t always come with pain. A nosebleed that won’t stop. Gums that bleed when you brush. Unexplained swelling in your legs. Purple patches under your skin. These aren’t normal. They’re red flags. And if you’re over 65, have high blood pressure, or have had a past bleed? Your risk jumps even higher. You don’t need to stop warfarin. But you do need to know what to watch for—and what to do before it turns into an emergency.

The posts below give you real, practical info: how to spot bleeding before it’s too late, why switching to a generic version can change your INR, what foods to avoid, and how to talk to your doctor when something feels off. You’ll find stories from people who’ve been there, and clear steps to take if you’re on warfarin and something doesn’t feel right. This isn’t theory. It’s what works when your life depends on catching it early.