Can aspirin cause bleeding on the brain?

October 14, 2025 •

3 min read

Recent studies have shown that for older adults without a history of heart disease, daily low-dose aspirin can increase the risk of intracranial bleeding by a statistically significant percentage compared to a placebo. This growing body of evidence has shifted medical guidelines, bringing the question, 'Can aspirin cause bleeding on the brain?', to the forefront of patient-physician discussions. While aspirin's blood-thinning properties are beneficial for preventing clot-related issues, this same effect carries a risk of serious bleeding complications.

Quick Summary

Aspirin, an antiplatelet medication, increases the risk of bleeding on the brain, particularly in older adults using it for primary prevention. Recent medical guidelines emphasize careful risk assessment, as the potential harms often outweigh the benefits for those without a prior history of cardiovascular events.

Key Points

Bleeding Risk is Real: Aspirin's antiplatelet action can significantly increase the risk of intracranial hemorrhage, a serious form of brain bleeding.
Age is a Major Factor: The risk of a brain bleed is higher in older adults, who often have more fragile blood vessels and are at greater risk of falls.
Primary vs. Secondary Prevention: Medical guidelines have shifted away from recommending aspirin for primary prevention (preventing a first event) in many populations, but it remains a critical therapy for secondary prevention (preventing recurrence).
Individualized Assessment is Key: The decision to take aspirin should be made in consultation with a doctor, who can weigh your specific cardiovascular risk against your bleeding risk.
Certain Populations Face Higher Risk: Studies have shown that individuals of Asian ethnicity and those with a low body mass index may have a heightened risk of intracerebral hemorrhage when taking aspirin.
Don't Stop Aspirin Abruptly: Patients currently taking aspirin should not stop the medication suddenly without consulting their healthcare provider, as this could increase the risk of a clot-related event.
Watch for Symptoms: Anyone taking aspirin should be aware of the warning signs of a brain bleed, such as a severe headache, confusion, or speech problems, and seek immediate medical attention if they occur.

Aspirin, or acetylsalicylic acid, is a widely used medication known for its ability to relieve pain and reduce fever. One of its key effects is its antiplatelet activity, which is important for cardiovascular health. Aspirin inhibits an enzyme involved in platelet clumping, which helps prevent blood clots. This is beneficial for preventing heart attacks and ischemic strokes but also increases the risk of bleeding, including potentially serious bleeds in the brain.

The Mechanism Behind Aspirin-Induced Bleeding

Aspirin's anti-clotting effects interfere with the body's natural ability to stop bleeding if a blood vessel in the brain ruptures. By disabling platelets, it makes forming a stable clot more difficult, potentially leading to a hemorrhagic stroke or other intracranial bleeding. The antiplatelet effect of aspirin can last for about seven to ten days.

Factors That Increase Brain Bleed Risk

Several factors can increase the risk of aspirin-related brain bleeds, including advanced age, ethnicity, BMI, underlying medical conditions like uncontrolled high blood pressure, and taking other NSAIDs or blood thinners. Studies show increased intracranial bleeding with low-dose aspirin for primary prevention in older adults.

Shifting Medical Guidelines: Primary vs. Secondary Prevention

Evidence of bleeding risks, especially intracranial hemorrhage, has led to updated guidelines for aspirin use. Recommendations advise against starting aspirin for primary prevention in older adults. The decision requires individualized risk and benefit assessment.

Aspirin Use: Primary vs. Secondary Prevention


Feature	Primary Prevention	Secondary Prevention
Patient Population	Individuals without a prior history of heart attack or stroke.	Individuals with a prior history of a heart attack or clot-related (ischemic) stroke.
Goal of Therapy	To prevent a first-time cardiovascular event.	To prevent a recurrent cardiovascular event.
Risk-Benefit Balance	Often unfavorable, especially for older adults, as the risk of serious bleeding can outweigh the potential benefits of preventing a first event.	Typically favorable, as the risk of a recurrent clot-related event is high, and the benefits of aspirin usually outweigh the bleeding risk.
Current Medical Advice	Not recommended for routine use, especially in older adults. Requires careful, individualized discussion with a healthcare provider.	A cornerstone of treatment and generally recommended by a healthcare provider.
Special Considerations	Particular caution with older age, high blood pressure, other bleeding risks, and low BMI.	Careful monitoring is still necessary, but the strong evidence for preventing re-occlusion makes it a standard of care.

Steps to Mitigate Bleeding Risk

To help manage bleeding risk when taking aspirin:

Discuss your medical history, including any history of bleeding or high blood pressure, with your doctor.
Review all medications and supplements with your doctor to identify potential interactions, especially with other NSAIDs or blood thinners.
Consider lifestyle changes to reduce fall risk, particularly for older adults.
Be aware of symptoms of a brain bleed and seek immediate medical help if they occur.
Never start or stop a daily aspirin regimen without consulting your doctor.

Conclusion

Yes, aspirin poses a risk of causing bleeding on the brain due to its antiplatelet properties. The risk is particularly relevant for primary prevention, especially in older adults and certain other populations. Guidelines recommend an individualized approach. Consulting with a healthcare provider is essential.

Frequently Asked Questions

Aspirin works as an antiplatelet agent, preventing platelets from clumping, which helps prevent blood clots but also impairs the body's ability to stop bleeding, potentially leading to a hemorrhagic stroke if a brain blood vessel ruptures.

Older adults have a higher risk. Other risk factors include a history of cerebral amyloid angiopathy (CAA), uncontrolled high blood pressure, low body mass index, and Asian ethnicity.

New guidelines advise against routinely starting daily aspirin for primary prevention in older adults. For these individuals, bleeding risk often outweighs benefit. For secondary prevention, aspirin may still be recommended.

Warning signs include a sudden, severe headache; confusion; difficulty speaking; weakness or numbness on one side; vision changes; and dizziness. Seek immediate medical help if these occur.

Yes, taking aspirin with other NSAIDs (like ibuprofen) or blood-thinning medications (anticoagulants) can significantly increase bleeding risk.

No, never stop prescribed daily aspirin without consulting your doctor. Stopping abruptly could increase your risk of a clot-related event.

Doctors consider a patient's cardiovascular risk versus individual bleeding risk factors like age, medical history, and other medications. For low cardiovascular risk, bleeding risk may be too high. For those with a history of heart attack or stroke, benefits typically outweigh risks.