Safety & Warning Signs

Why You Need to Know the Warning Signs

Warfarin saves lives by preventing dangerous blood clots. But because it changes how your blood clots, it also creates risks. The two main dangers are bleeding (when your INR is too high and your blood is too thin) and clotting (when your INR is too low and your blood is not thin enough).

You cannot feel your INR number. You cannot tell from how you feel whether you are at 2.5 or 5.0. That is why you need to know the physical warning signs that tell you something may be wrong. Catching these signs early can be the difference between a minor dose adjustment and a medical emergency.

Bleeding Warning Signs vs. Clotting Warning Signs

Bleeding and clotting present very differently. Recognizing which one you may be experiencing helps you communicate clearly with your doctor or emergency services.

If you are unsure whether a symptom is serious, always err on the side of caution. Call your doctor or anticoagulation clinic. If you cannot reach them and the symptom is worsening, go to the emergency room.

When to Call Your Doctor (Non-Emergency)

Not every symptom is a 911 emergency, but some still need prompt medical attention. Contact your doctor or anticoagulation clinic if:

• You notice new or increased bruising
• You have a nosebleed that stops but keeps recurring
• You see a small amount of blood in your urine or stool
• Your gums bleed more than usual
• You get a minor cut that takes longer to stop bleeding
• You miss one or more warfarin doses
• You start a new medication, supplement, or herbal product
• You are sick with fever, vomiting, or diarrhea (these affect INR)
• You change your diet significantly
• You get an INR result that is out of your target range

Your clinic would rather hear from you about a minor concern than deal with a serious event that could have been prevented. Do not hesitate to call.

Daily Safety Tips for Warfarin Patients

Living safely on warfarin is mostly about developing good habits and reducing your risk of injury. Here are practical tips for everyday life:

At Home

• Use an electric razor instead of a blade razor to reduce the risk of cuts.
• Use a soft-bristled toothbrush to protect your gums.
• Be careful with sharp knives and kitchen tools. If you cut yourself, apply firm pressure for at least 10 minutes.
• Remove tripping hazards like loose rugs, cluttered walkways, and cords on the floor. Falls are one of the biggest risks.
• Use non-slip mats in the bathroom.
• Wear shoes or slippers with good grip rather than walking barefoot or in socks on smooth floors.

Exercise and Activities

• Avoid contact sports (football, hockey, martial arts, boxing) where head injuries or severe bruising are likely.
• Low-impact exercise like walking, swimming, cycling, yoga, and light weight training is safe and encouraged.
• Always wear a helmet when cycling or skiing.
• If you garden, wear thick gloves to protect against cuts and thorns.

Medical Situations

• Wear a medical alert bracelet or necklace that says you take warfarin.
• Carry a card in your wallet listing your medication, dose, target INR, and emergency contact.
• Before any dental work, tell your dentist you are on warfarin. You may need antibiotics to prevent endocarditis, and your dentist may coordinate with your anticoagulation clinic about whether to adjust your dose.
• Before any surgery or medical procedure, inform the surgeon and anesthesiologist. Warfarin usually needs to be paused before surgery, with a bridging plan for anticoagulation.

A Special Note About Head Injuries

If you fall and hit your head — even if you feel completely fine afterward — you should seek medical evaluation. Warfarin increases the risk of intracranial bleeding (bleeding inside the skull), which can develop slowly over hours or even days after the initial injury. Symptoms may not appear immediately.

After a head injury, watch for: worsening headache, drowsiness, confusion, vision changes, nausea or vomiting, weakness on one side, or any change in behavior. If any of these appear, go to the emergency room immediately.

What to Keep at Home

• Gauze pads and bandages for minor cuts
• A blood pressure monitor (helpful but not required)
• Your anticoagulation clinic phone number on speed dial
• Your current medication list and INR log, printed or on your phone
• A medical alert bracelet or card

Sources

1. American Heart Association. “A Patient's Guide to Taking Warfarin.” AHA/ACC Guidelines, 2022. heart.org
2. Holbrook A, et al. “Evidence-based management of anticoagulant therapy.” Chest, 2012;141(2 Suppl):e152S–e184S. doi:10.1378/chest.11-2295
3. National Stroke Association. “Stroke Warning Signs and Symptoms.” stroke.org
4. Ageno W, et al. “Oral anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis.” Chest, 2012;141(2 Suppl):e44S–e88S. doi:10.1378/chest.11-2292