Does aspirin actually prevent migraines?
The short answer is: possibly, but the evidence is not as strong as for newer prescription drugs. A 2020 review in The American Journal of Medicine looked at the totality of randomized trial data and concluded that daily aspirin at doses of 81–325 mg 'may be an effective and safe treatment option for the prevention of recurrent migraine headaches' [4]. However, the same review notes that 'some, but not all, randomized trials' support this, meaning the results are inconsistent. In contrast, a 2021 phase 3 trial of the prescription drug atogepant showed a clear, dose-dependent reduction in migraine days: 3.7 fewer days per month with 10 mg, 3.9 with 30 mg, and 4.2 with 60 mg, compared to 2.5 with placebo [2]. That is a much larger and more reliable effect than what aspirin studies typically show.
Why the difference? Aspirin's mechanism for migraine prevention is not fully understood, but it likely involves its anti-inflammatory and antiplatelet effects [4][5]. The problem is that most aspirin prevention studies are older, smaller, and less rigorous than modern drug trials. The 2020 review itself calls the evidence 'totality of evidence' rather than citing a single definitive trial [4]. So while aspirin may help some people, it is not a guaranteed solution.
When is aspirin a good choice for migraine prevention?
Aspirin's main advantages are its low cost, wide availability, and generally favorable side effect profile [4]. For people without health insurance or with high prescription co-pays, daily low-dose aspirin (81 mg, or 'baby aspirin') is a reasonable option to try, especially if they have infrequent migraines and no contraindications like bleeding risk or stomach ulcers [4][6]. The 2020 review specifically highlights that for patients who cannot afford or tolerate prescription drugs, aspirin provides an 'additional option' [4].
However, aspirin is not a first-line preventive for most people with frequent or severe migraines. The newer calcitonin gene-related peptide (CGRP) antagonists like atogepant are far more consistently effective, as shown by the 2021 trial where even the lowest dose (10 mg) outperformed placebo by a clear margin [2]. Additionally, a 2023 study on predictors of acute migraine treatment response found that aspirin (acetylsalicylic acid, ASA) was less effective than caffeine combination products for achieving 2-hour pain freedom and 24-hour pain relief [3]. That study looked at acute treatment, not prevention, but it suggests that aspirin may not be the best choice for everyone.
There is also a specific population where aspirin has proven benefit: pregnant women at high risk for preeclampsia. The US Preventive Services Task Force recommends low-dose aspirin (81 mg/day) starting after 12 weeks of gestation for preeclampsia prevention [7]. Interestingly, a 2023 study found that women with migraine who took aspirin regularly before pregnancy had a lower risk of preterm delivery (RR 0.55 for ≥2 times/week) [1]. This suggests that for some women, aspirin may have dual benefits, but this is not a general recommendation for migraine prevention.
What are the downsides of using aspirin for migraine prevention?
The biggest risk with daily aspirin is bleeding. The US Preventive Services Task Force, in its 2022 guidelines on aspirin for cardiovascular prevention, concluded that for adults 60 or older, starting low-dose aspirin has 'no net benefit' because the bleeding risk outweighs any potential gain [6]. For adults aged 40–59 with a 10% or higher 10-year cardiovascular risk, the decision should be individual, and only for those not at increased bleeding risk [6]. These same bleeding risks apply if you take aspirin for migraine prevention.
Another limitation is that the evidence for aspirin's preventive effect is not strong enough to guarantee results. The 2020 review explicitly says the data come from 'some, but not all, randomized trials' [4]. That means you might take it daily and still get no benefit. In contrast, the atogepant trial showed a statistically significant and clinically meaningful reduction in migraine days across all doses [2]. So if you have tried aspirin and it didn't work, you are not alone, and you should talk to your doctor about prescription options.
Finally, aspirin can cause gastrointestinal side effects like nausea and constipation, though these are less common with low doses [4]. The 2021 atogepant trial reported constipation in 6.9–7.7% of participants and nausea in 4.4–6.1% [2], so both options have some side effects. The key is to weigh the modest, uncertain benefit of aspirin against its known risks, and to consider newer, more effective alternatives if your migraines are frequent or disabling.
About These Sources
This answer is built on 7 peer-reviewed studies — published from 2020 to 2023, 4 in Q1 journals, collectively cited 1,008 times — selected as the most relevant from 10 studies that passed quality screening, drawn from 46 papers retrieved from a database of over 500 million.
Sources used in this answer
Prepregnancy Migraine, Migraine Phenotype, and Risk of Adverse Pregnancy Outcomes
In 30,555 pregnancies, women with migraine had higher risks of preterm delivery (RR 1.17) and preeclampsia (RR 1.40); regular aspirin use (≥2×/week) was associated with a 45% lower risk of preterm delivery (RR 0.55) [2].
Atogepant for the Preventive Treatment of Migraine
In a phase 3 RCT of 873 participants, atogepant (10–60 mg daily) reduced migraine days by 3.7–4.2 per month vs. 2.5 with placebo over 12 weeks (P<0.001 for all doses) [3].
Predictors of treatment‐response to caffeine combination products, acetaminophen, acetylsalicylic acid (aspirin), and nonsteroidal anti‐inflammatory drugs in acute treatment of episodic migraine
In 2,224 people with episodic migraine, aspirin (ASA) was less effective than caffeine combination products for acute pain relief; only lower symptom severity predicted better response to aspirin [5].
Aspirin in the Treatment and Prevention of Migraine Headaches: Possible Additional Clinical Options for Primary Healthcare Providers.
A review of randomized trials concluded that high-dose aspirin (900–1300 mg) is effective for acute migraine, and daily low-dose (81–325 mg) may prevent recurrent attacks, though not all trials agree [7].
Prevention of preeclampsia with aspirin.
A review of preeclampsia prevention trials found that low-dose aspirin (150 mg) started before 16 weeks reduces preterm preeclampsia by 62% in high-risk women [8].
Aspirin Use to Prevent Cardiovascular Disease
The USPSTF recommends against starting low-dose aspirin for primary CVD prevention in adults ≥60 (D recommendation) and advises individual decision for ages 40–59 with ≥10% 10-year CVD risk (C recommendation) [9].
Aspirin Use to Prevent Preeclampsia and Related Morbidity and Mortality
The USPSTF recommends low-dose aspirin (81 mg/day) after 12 weeks of gestation for pregnant persons at high risk for preeclampsia to reduce preeclampsia, preterm birth, and perinatal mortality (B recommendation) [10].