Blood Thinners Before Endoscopy

Anticoagulants and antiplatelet medicines (“blood thinners”)

Warfarin, direct oral anticoagulants (such as apixaban, rivaroxaban, dabigatran, edoxaban), heparin injections, aspirin, clopidogrel, ticagrelor, prasugrel

Anticoagulants slow the blood’s clotting system, and antiplatelet medicines stop platelets from sticking together. They prevent strokes, heart attacks and clots in the legs and lungs. During endoscopy, taking a tissue sample or removing a polyp can make a small wound in the gut lining, and a blood thinner can make it bleed more. The doctor must balance the risk of bleeding against the risk of a clot if the medicine is paused, and this balance is different for each person and each procedure.

Tell the endoscopy team well before your procedure about ALL blood thinners, including aspirin and any injections, why you take them, and any recent stent, valve, stroke or clot. Your doctor will give you written instructions: for some procedures (a diagnostic gastroscopy or colonoscopy without polyp removal) many people continue their medicine; for others, such as removing larger polyps or certain therapeutic procedures, the medicine may need to be paused for a set number of days, sometimes with a short-acting injection to cover the gap. Do not stop, change or restart any of these medicines yourself, because stopping some of them can cause a stroke, heart attack or clot. Ask exactly when to stop and when to restart, and write it down. Do not stop aspirin or other antiplatelet drugs without being told to do so, especially if you have a heart stent.

• Black, tarry stools; red blood in the stool; or vomiting blood or “coffee-ground” material, in the days or even up to a couple of weeks after a procedure — Possible bleeding from the biopsy or polyp site. Go to the emergency department immediately and tell staff you take blood thinners.

• Dizziness, fainting, a racing heart or looking very pale — May mean significant blood loss. Call emergency services or go to the emergency department now.

• Severe or worsening belly pain, a hard swollen belly, or fever after the procedure — Could be a perforation or other complication. Go to the emergency department now.

• If a blood thinner was paused: sudden weakness of the face, arm or leg, speech difficulty, chest pain, sudden breathlessness, or a painful swollen leg — These may be signs of a stroke, heart attack or clot. Call emergency services now.

Many medicines and supplements interact with blood thinners, including some antibiotics, anti-inflammatory painkillers (NSAIDs), and herbal products such as ginkgo, garlic or ginger supplements, turmeric and fish oil in high amounts. Warfarin also reacts to changes in vitamin K intake (green leafy vegetables) and alcohol. Never start or stop anything without checking with your pharmacist or doctor.

If you take warfarin, an INR blood test is usually done in the days before the procedure and after restarting. Kidney function may be checked for some newer anticoagulants because it affects how long to pause them. Your doctor may arrange a plan with your cardiologist, haematologist or family doctor.

Only stop or restart a blood thinner exactly as instructed by the doctor who knows your heart and clot history and your procedure plan. If you are unsure, call the endoscopy unit before the day of your procedure rather than guessing.

Some blood thinners (for example warfarin and some newer tablets) are not suitable in pregnancy, and injections may be used instead. Anyone who is pregnant or planning pregnancy should discuss their treatment with their doctor before any procedure.

• Which of my medicines are blood thinners, and do I need to pause any for my procedure?

• Exactly which day do I stop, and which day do I restart?

• Do I need a bridging injection while it is paused?

• Should my heart doctor or haematologist be involved?

• What bleeding signs should I watch for after the procedure, and for how many days?

This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the Approved for publication by SGA; individual clinician review is ongoing. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.