Does daily low-dose aspirin prevent strokes in healthy older adults?
No, it does not prevent strokes in healthy older adults, and it significantly increases the risk of dangerous bleeding. The landmark ASPREE trial, which followed over 19,000 healthy adults aged 70 and older for nearly 5 years, found that taking 100 mg of aspirin daily did not reduce the number of ischemic strokes (the most common type, caused by a clot) [1][5]. In fact, the aspirin group had a 38% higher risk of intracranial bleeding (bleeding inside the skull) compared to the placebo group (1.1% vs. 0.8%) [1][5]. This means that for every 1,000 healthy older adults taking aspirin for about 5 years, roughly 3 more people will suffer a serious brain bleed, while no one will be spared a stroke. This finding is consistent across the ASPREE trial's multiple analyses [1][5].
What other harms should healthy older adults consider?
Beyond bleeding in the brain, daily low-dose aspirin causes several other significant harms in healthy older people. The ASPREE trial showed that aspirin increased the risk of developing anemia by 20% (51.2 vs. 42.9 cases per 1,000 person-years) [2]. This was linked to a drop in iron stores (ferritin levels), even in people who did not have a major bleeding event, suggesting that aspirin causes low-level, chronic blood loss that depletes the body's iron [2]. The study authors recommended that older adults on aspirin should have their hemoglobin checked periodically [2].
Surprisingly, aspirin also increased the risk of serious falls requiring hospitalization by 17% (884 vs. 804 falls) [3]. This is a major concern because falls are a leading cause of injury and loss of independence in older adults. The same study found that aspirin did not prevent fractures [3]. Furthermore, aspirin did not reduce the risk of becoming frail over time, as measured by two different standard definitions of frailty [6][7]. So, for a healthy older person, aspirin offers no protection against the common problems of aging like falls, fractures, or frailty, and it actually makes some of them more likely.
Is there any benefit at all for healthy older adults?
The only potential benefit seen in the ASPREE trial was a 15% reduction in the risk of developing type 2 diabetes over about 5 years (6.1% of participants developed diabetes overall) [4]. This is an interesting finding, likely related to aspirin's anti-inflammatory effects. However, this benefit came with a steep price: the same study reported a 44% increase in major bleeding events (3.7% vs. 2.6%) [4]. When weighing a modest reduction in diabetes risk against a clear increase in serious, life-threatening bleeding, the balance tips heavily toward harm. No study in this set found that aspirin reduced the risk of heart attack, stroke, or death in healthy older adults. For individuals who have already had a heart attack or stroke, the benefit-risk calculation is different, and a doctor may still recommend aspirin. But for healthy older adults without such a history, the evidence is clear: the risks outweigh the benefits.
About These Sources
This answer is built on 7 peer-reviewed studies — published from 2021 to 2023, 6 in Q1 journals, collectively cited 159 times — selected as the most relevant from 9 studies that passed quality screening, drawn from 42 papers retrieved from a database of over 500 million.
Sources used in this answer
Low-Dose Aspirin and the Risk of Stroke and Intracerebral Bleeding in Healthy Older People
In the ASPREE randomized trial of 19,114 healthy older adults, daily low-dose aspirin did not significantly reduce ischemic stroke (HR 0.89) but significantly increased intracranial bleeding (1.1% vs. 0.8%, HR 1.38).
Effect of Low-Dose Aspirin Versus Placebo on Incidence of Anemia in the Elderly
A post-hoc analysis of the ASPREE trial found that aspirin increased the risk of incident anemia by 20% (51.2 vs. 42.9 events per 1000 person-years) and caused a greater decline in ferritin levels, independent of major bleeding.
Daily Low-Dose Aspirin and Risk of Serious Falls and Fractures in Healthy Older People
In the ASPREE-FRACTURE substudy of 16,703 participants, aspirin did not reduce fracture risk (HR 0.97) but was associated with a 17% higher rate of serious falls leading to hospitalization.
Daily low-dose aspirin and incident type 2 diabetes in community-dwelling healthy older adults: a post-hoc analysis of efficacy and safety in the ASPREE randomised placebo-controlled trial
A post-hoc analysis of the ASPREE trial found that aspirin reduced the risk of incident type 2 diabetes by 15% (HR 0.85) but increased major bleeding by 44% (HR 1.44) in healthy older adults.
Low-Dose Aspirin and the Risk of Stroke and Intracerebral Bleeding in Healthy Older People: Secondary Analysis of a Randomized Clinical Trial.
This secondary analysis of the ASPREE trial (same data as paper 1) confirmed that aspirin did not reduce ischemic stroke (HR 0.89) but significantly increased intracranial bleeding (HR 1.38) in healthy older adults.
The Effect of Low-Dose Aspirin on Frailty Phenotype and Frailty Index in Community-Dwelling Older Adults in the ASPirin in Reducing Events in the Elderly Study
In the ASPREE trial, low-dose aspirin did not reduce the risk of incident frailty over a median of 4.7 years, whether measured by the Fried frailty phenotype (HR 1.04) or a frailty index (HR 1.03).
The Effect of Low-Dose Aspirin on Frailty in Older Adults in the Aspirin in Reducing Events in the Elderly Study
This analysis of the ASPREE trial (same data as paper 8) confirmed that aspirin did not reduce incident frailty by either the Fried definition (HR 1.03) or the frailty index (HR 1.03).