GLP-1 and warfarin: INR changes to watch
If you take warfarin (a blood thinner) and start a GLP-1 medicine, your INR blood test may need closer checks. The good news: a few simple habits keep you safe.
Some people take a blood thinner called warfarin. It stops dangerous clots in your body. Doctors track it with a blood test called INR. If you also take a GLP-1 medicine for weight or sugar, this test can change. This short guide explains what to watch, in plain words.
What the medicine labels say
The Wegovy label says it 'causes a delay of gastric emptying.' That means food and pills leave your stomach slower. This can change how other pills get absorbed. The same label adds: 'Consider increased clinical or laboratory monitoring for medications that have a narrow therapeutic index.' Warfarin is one of those. A tiny change in it can matter a lot. In formal studies, the Ozempic label says 'No clinically relevant drug-drug interaction with semaglutide... was observed' for warfarin. So big changes are rare. But watching closely is still the rule.
GLP-1 medicines always make warfarin unsafe.
mostly falseMostly false, explained simply. Formal tests showed no big INR change in most people. But the Ozempic label used in Europe notes 'cases of decreased INR have been reported during concomitant use of acenocoumarol and semaglutide.' Acenocoumarol is a warfarin cousin. So a few people did see their INR drop. The fix is simple: check INR more often when you start or raise the GLP-1. Once it is steady, you relax.
Your INR checklist at each GLP-1 step
Stay safe: simple habits
The bottom line
GLP-1 and warfarin can work together safely. The trick is closer INR checks when you start or raise the GLP-1, and letting your doctor adjust the warfarin. Watch for bruising, keep vitamin K steady, and never change warfarin on your own.