Can I Take Blood Thinners with an Unruptured Brain Aneurysm?

If you have been diagnosed with an unruptured brain aneurysm, it is completely normal to be afraid that taking aspirin, anticoagulants, or other blood thinners might cause it to bleed. However, having an unruptured aneurysm is not, by itself, a reason to stop taking a medically necessary blood thinner. Current evidence has not clearly shown that these medications cause aneurysms to form or rupture ^[1]. It is critical that you do not stop taking your prescribed medications without talking to your doctor. Depending on why you take them, stopping abruptly can substantially increase your risk for life-threatening blood clots, heart attacks, or strokes ^[2].

Do Blood Thinners Increase the Risk of Rupture?

Current observational studies have not shown a clear link between these medications and an increased risk of an aneurysm bursting. However, the evidence is limited and cannot guarantee zero risk, which is why your doctors will evaluate your case individually ^[3].

• Antiplatelets (like aspirin or clopidogrel): For small aneurysms (under 7 millimeters), some observational studies suggest aspirin might actually be associated with a lower risk of the aneurysm growing or rupturing ^[1][4]. Researchers think aspirin might have an anti-inflammatory effect on the aneurysm wall ^[5]. However, these findings do not mean aspirin protects all aneurysms. Medical guidelines state you should never start taking aspirin solely to protect your aneurysm, as it carries its own bleeding risks ^[6].
• Anticoagulants (like warfarin or direct oral anticoagulants): These are stronger blood thinners. The evidence here is less extensive, but current studies of patients with aneurysms taking these medications have not demonstrated an increased risk of rupture ^[3][7].

Understanding Your Medications

Complicating a Bleed vs. Causing a Bleed

It is helpful to understand the difference between a medication causing a rupture and complicating a rupture. Blood thinners do not pop the aneurysm. However, they are designed to prevent your blood from clotting. If your aneurysm were to rupture for other reasons, having active blood thinners in your system can make the emergency bleeding more severe and harder to control ^[8][9].

Because of this, your medical team will carefully weigh your specific rupture risk—based on the aneurysm’s size, shape, location, and your blood pressure—against your risk of developing dangerous blood clots ^[10].

Why You Should Not Stop Your Medication Independently

Your doctor prescribed your blood thinner for a very important reason. Only your prescribing clinician (such as your cardiologist or primary care doctor) and your aneurysm specialist can properly compare the risks of continuing versus stopping your specific medication ^[11].

Important Steps You Can Take:

• Control other risks: High blood pressure and smoking are major risk factors for aneurysm growth and rupture. Keeping your blood pressure controlled and quitting smoking are powerful, proven ways to protect yourself ^[1][12].
• Avoid unauthorized medications: Do not take over-the-counter NSAIDs (like ibuprofen or naproxen), extra aspirin, or herbal supplements without asking your doctor or pharmacist, as these can significantly increase your bleeding risk when combined with prescribed thinners.

What Happens Before Surgery or Dental Procedures?

If you need a procedure, your doctors will create a customized medication plan.

• Dental work and minor procedures: Many dental procedures can actually be done safely without interrupting your blood thinners. Never stop your medication based on a dentist’s or surgeon’s advice alone; any plan to pause medication must be directed by the clinician who originally prescribed it ^[11].
• Non-aneurysm surgeries: If you must pause your medication, your doctors will provide a specific timeline based on your kidney function, the exact drug you take, and the surgery’s bleeding risk ^[13].
• Aneurysm treatments: Some minimally invasive aneurysm treatments—such as placing a stent or flow diverter (a tiny mesh tube placed inside the artery)—actually require you to take antiplatelet medications before and after the procedure to prevent clots from forming on the device ^[14].

When to Seek Emergency Care

Do not wait for a routine appointment if you experience signs of a rupture or severe bleeding. Call emergency services (like 911) immediately if you experience:

• A sudden, severe headache that reaches maximum intensity rapidly (often described as the “worst headache of your life”)
• Neck stiffness, vomiting, fainting, or loss of consciousness
• New weakness, numbness, trouble speaking, or confusion
• Signs of severe medication-related bleeding, such as vomiting blood, black or bloody stools, or uncontrolled bleeding from an injury.