Based on PubMed | Is blurred vision a side effect of warfarin, and when should I seek medical attention if it occurs?

Blurred Vision and Warfarin: What You Need to Know

Blurred or changed vision can occur while taking warfarin, and it should be taken seriously because it can signal bleeding in or around the eye or other complications related to anticoagulation. Vision changes are listed among symptoms to watch for while on warfarin and warrant prompt attention. ^[1] If you notice new blurred vision, double vision, dark spots, or a sudden decrease in sight, it’s safest to seek medical care urgently. ^[2]

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How warfarin could affect your eyes

Warfarin reduces your blood’s ability to clot, which lowers the risk of harmful clots but raises the chance of bleeding in various tissues, including the eye. ^[3] Although serious eye bleeding is uncommon, cases of spontaneous bleeding inside the eye (such as subretinal, suprachoroidal, or anterior chamber hemorrhage) have been reported in people on warfarin, sometimes even when the INR the blood test used to monitor warfarin was in the therapeutic range. ^[4] Such hemorrhages can cause symptoms like sudden blurred vision, shadowing, floaters, eye pain, or a curtain-like loss of sight. ^[5]

Certain conditions may increase the risk of warfarin-associated ocular bleeding. Age-related macular degeneration and high blood pressure have been noted as risk factors for large subretinal hemorrhages in people taking anticoagulants, which can severely impact vision. ^[6] In rare instances, significant suprachoroidal hemorrhage associated with anticoagulation has led to poor visual outcomes. ^[7]

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When to seek medical attention

Treat any new or worsening vision changes while on warfarin as urgent. ^[2] Get immediate medical care if you experience sudden blurred vision, partial or complete loss of vision, a new curtain or shadow, flashes, many new floaters, eye pain, or severe headache with visual symptoms. ^[2] Bleeding signs in other areas (such as black or bloody stools, red or dark urine, unusual bruising, persistent headache, dizziness, or weakness) alongside vision changes also warrant prompt evaluation. ^[3]

If visual symptoms are mild and brief but recur, contact your prescriber quickly to review your INR and overall bleeding risk, as dose adjustments or interaction checks may be needed. ^[3] Do not stop warfarin on your own, because sudden discontinuation can raise the risk of dangerous clots; decisions about holding or adjusting warfarin should be guided by a clinician after assessment. ^[8]

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Practical steps if blurred vision occurs

• Seek urgent care: Sudden or significant vision changes should be evaluated in an emergency or urgent ophthalmology setting. ^[2]
• Bring your warfarin details: Share your current dose, last INR value, and any recent changes or missed doses. ^[3]
• List all medications and supplements: Other drugs can interact with warfarin and increase bleeding risk, so clinicians will want a full list. ^[1]
• Avoid risky activities: While symptoms are being evaluated, minimize activities that might cause trauma and additional bleeding. ^[3]

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Monitoring and prevention tips

Regular INR monitoring and consistent dosing are key to balancing clot prevention with bleeding risk. ^[3] Report unusual symptoms promptly, including any visual changes, so that potential problems are addressed early. ^[2] Be alert to skin changes like painful discoloration or sores within days of starting therapy, which can indicate rare complications needing immediate care. ^[1] Coordinate care around eye procedures carefully, as stopping warfarin for ophthalmic interventions involves weighing bleeding risks against clotting risks. ^[9]

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Summary

• Blurred or changed vision can occur on warfarin and may indicate eye bleeding or other complications. ^[1]
• Treat sudden or significant vision symptoms as urgent and seek medical attention right away. ^[2]
• Do not stop warfarin without medical guidance; instead, have your INR and medications reviewed promptly. ^{[8] [3]}
• Certain conditions (like macular degeneration and high blood pressure) may heighten the risk of serious ocular hemorrhages on anticoagulation. ^[6]

If you experience any vision changes while taking warfarin, getting evaluated quickly helps protect your sight and ensures your anticoagulation remains safe and effective. ^{[2] [3]}