Taking a blood thinner at home: warfarin, blood tests and bleeding signs

Blood thinners prevent dangerous clots, and they also make bleeding more likely. Warfarin in particular needs regular blood tests and some care with food and other medicines. This note covers the essentials for families managing warfarin at home. Newer blood thinners have different rules, so ask your pharmacist which ones apply to yours.

The INR test

Warfarin is checked with a blood test called the INR, sometimes called a PT test, at regular visits.¹ The result shows whether the dose is right. Keep every appointment, and write down each result and dose.

Keep vitamin K foods steady

Vitamin K affects how warfarin works. You don’t have to avoid foods with it, but keep the amount steady from day to day and week to week.¹ Foods with a lot of vitamin K include leafy greens like spinach, kale, collards and lettuce, broccoli, Brussels sprouts, raw green cabbage, parsley and green tea.¹ Check with the provider before a big change in diet.¹

Check before any other medicine

Ask the provider or pharmacist before taking any over-the-counter medicine, vitamin, supplement, cold medicine or antibiotic.¹ Avoid alcohol.¹ Don’t stop or change the dose before a procedure unless the prescriber says to.¹

Bleeding signs to call about

Call for bleeding gums or nosebleeds, blood in the urine, bloody or dark stool, vomiting blood, a lot of bruising or dark red or black bruises, headache, dizziness or weakness, or any heavy bleeding.¹ Call after a serious fall or any blow to the head, even if the person seems fine.¹

Prevent falls and cuts

Good lighting, no loose rugs or cords, and care on wet floors help prevent falls.¹ Use a soft toothbrush, waxed floss and an electric razor.¹

Tell everyone

Tell every doctor, nurse and dentist about the warfarin, and consider a medical alert bracelet.¹ A home health nurse can draw INR blood tests at home, review every medicine for interactions, and teach the family what to watch for.