Warfarin and NSAIDs: Risks, Interactions, and What You Need to Know

When you take warfarin, a blood thinner used to prevent dangerous clots in people with atrial fibrillation, artificial heart valves, or a history of deep vein thrombosis. Also known as Coumadin, it works by blocking vitamin K, which your body needs to form clots. Many people on warfarin also take NSAIDs, nonsteroidal anti-inflammatory drugs like ibuprofen, naproxen, or celecoxib, used for pain, swelling, or fever—but combining them isn’t as simple as popping two pills. This mix can raise your risk of serious bleeding, sometimes without warning.

Here’s why: NSAIDs irritate the stomach lining and reduce protective mucus, making ulcers more likely. Warfarin thins your blood. Together, they turn a small stomach irritation into a life-threatening bleed. Studies show people on both drugs have up to three times the risk of gastrointestinal bleeding compared to those on warfarin alone. Even occasional use of ibuprofen for a headache can push you over the edge. It’s not just stomach issues either—NSAIDs can also make warfarin work harder, causing your INR (the test that measures blood thinning) to spike unexpectedly. That’s why your doctor checks your INR regularly, especially when you start or stop an NSAID.

What can you do? First, talk to your pharmacist or doctor before taking any NSAID, even if it’s over-the-counter. Acetaminophen (Tylenol) is often a safer choice for pain relief if you’re on warfarin. If you must use an NSAID, keep it short-term and at the lowest dose possible. Avoid aspirin unless it’s prescribed for heart protection—it’s also an NSAID and carries the same risks. Watch for signs of bleeding: black or tarry stools, unusual bruising, gum bleeding, or sudden headaches. If you’re on warfarin, you’ve likely learned to track your diet, alcohol, and other meds. Now add NSAIDs to that list. It’s not about fear—it’s about awareness.

The posts below cover real cases and practical advice from people who’ve been there. You’ll find guides on managing drug interactions, recognizing bleeding risks, and choosing safer pain relief options. Some explain how to talk to your pharmacist about your full med list. Others break down what INR numbers really mean. This isn’t theory—it’s what works when your life depends on getting it right.