I have heard that taking an a pill of acetylsalicylic acid (ASA aka Aspirin) a day can help reduce the risk of heart disease, strokes, cancer and now Alzheimer's. From the linked article to WebMD:

We've long known that aspirin reduces the risk of heart attacks and strokes while increasing your chances of surviving them. But now this household drug may protect you in other ways, too.

Newer evidence indicates that aspirin can also reduce the risk of cancer of the colon, esophagus, stomach, rectum, and prostate. And most recently, the humble aspirin has offered the tantalizing possibility that it may help protect against Alzheimer's disease.

Has ASA been shown in peer-reviewed journals to significantly reduce the risk of heart disease, stroke, cancer, and Alzheimer's? Are there no associated risks that offset these benefits?

As an aside: If ASA has been shown to be so effective, I wonder why do we not put it in eg table salt.

  • 2
    Fun fact: we put iodine in (some) table salt because it has benefits without related side effects at the low doses caused.
    – Ben Brocka
    Feb 13, 2012 at 22:45
  • @BenBrocka: That's exactly what I had in mind when I mentioned table salt. Perhaps the aside is a question of the economic effect on ASA providers (i.e. mandatory production of ASA by lowest bidder) and their lobbying potential/rent seeking. Feb 13, 2012 at 23:53
  • @BenBrocka many countries have stopped putting iodine in table salt because of the questionable benefits and potential problems years ago.
    – jwenting
    May 1, 2023 at 8:39

2 Answers 2


Whew, lots of questions.

Does aspirin reduce risk of heart-disease or stroke?


The Antithrombotic Trialists' Collaboration published Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ. 2002 Jan 12;324(7329):71-86.

It found:

Aspirin (or another oral antiplatelet drug) is protective in most types of patient at increased risk of occlusive vascular events, including those with an acute myocardial infarction or ischaemic stroke, unstable or stable angina, previous myocardial infarction, stroke or cerebral ischaemia, peripheral arterial disease, or atrial fibrillation. Low dose aspirin (75-150 mg daily) is an effective antiplatelet regimen for long term use, but in acute settings an initial loading dose of at least 150 mg aspirin may be required.

They recommend aspirin (or equivalent) for known high risk people. They don't know if it is possible to generally detect high risk people from the healthy population. They don't recommend aspirin for everyone.

These results reinforce the value of ensuring that antiplatelet therapy with 75-150 mg aspirin daily (or some other effective antiplatelet regimen) is considered routinely for all such patients at high or intermediate risk of occlusive vascular events (more than about 2% a year), irrespective of whether they have already had a major vascular event. An unanswered question, however, is whether it is possible to identify particular groups of apparently healthy people who may be at increased risk of myocardial infarction or stroke and for whom the benefits of daily aspirin outweigh the hazards. This is currently being investigated in an analysis of primary prevention trials. For most healthy individuals, however, for whom the risk of a vascular event is likely to be substantially less than 1% a year, daily aspirin may well be inappropriate.

(Note: An errata has been applied to this section.)

Does aspirin reduce risk of cancers?

Kind of. Maybe. No. Cancer is a big area; it isn't a single disease.

Aspirin reduces the chance of some cancers from recurring. For example:

There was evidence from three pooled [Randomly Controlled Trials] that [Aspirin] significantly reduces the recurrence of sporadic adenomatous polyps after one to three years. There is evidence from short-term studies to support regression, but not elimination or prevention of [colorectal adenomas] in [familial adenomatous polyposis].

Wikipedia has a reasonable discussion on some of the still-too-early-to-tell results, which includes:

  • Not helpful for prostate.
  • Mixed results for pancreatic.
  • Some evidence for colon, and lung.
  • Inconclusive for upper GI tract.

Does aspirin reduce risk of Alzheimer's disease?

The jury is still out.

This paper found that aspirin may help:

As expected, there was an inverse association between nonsteroidal anti-inflammatory drugs and aspirin (and unexpectedly angiotensin-converting enzyme inhibitors) and AD. This association was not observed with vascular dementia or any other diagnoses. Analysis showed no evidence for a dosage effect, ie, responses were equivalent for low and high doses.

Whereas this one suggests it may harm:

This paper concluded it didn't help existing Alzheimer's patients:

Although aspirin is commonly used in dementia, in patients with typical [Alzheimer's Disease] 2 years of treatment with low-dose aspirin has no worthwhile benefit and increases the risk of serious bleeds.

Conflicting studies? Time to look for a meta-analysis. The Cochrane Collaboration don't know yet, but they plan to find out.

Does aspirin have any adverse side-effects?

Yes. Many, many side-effects - generally mild or rare.

This (unreferenced, but likely reliable) pharmaceuticals site lists many of them. Here are some reduced highlights:

  • Gastrointestinal, including gastric mucosal lesions (very common), epigastric distress (very common), gastrointestinal bleeding (common in the elderly), hemorrhage, peptic ulcers, perforation, small bowel enteropathy, and esophageal ulcerations and maybe appendicitis.

  • Renal, including decreases in renal blood flow. High doses of NSAIDs in some high risk groups has (rarely) produced acute renal failure.

  • Hematologic, such as increased blood fibrinolytic activity. Rare cases of hypoprothrombinemia, thrombocytopenia, thrombocyturia, megaloblastic anemia, and pancytopenia. I have no idea what any of those mean, but they don't sound fun at all.

  • Hypersensitivity, including bronchospasm, rhinitis, conjunctivitis, urticaria, angioedema, and anaphylaxis. Commonly a problem amongst asthmatics.

  • Dermatologic, including Stevens-Johnson syndrome and a lichenoid eruption.

  • Hepatic, including hepatotoxicity and cholestatic hepatitis.

  • Oncologic, maybe pancreatic cancer, which is a particularly horrible cancer.

  • Metabolic, including dehydration and hyperkalemia.

  • Cardiovascular, including salicylate-induced variant angina, ventricular ectopy, conduction abnormalities, and hypotension.

  • Nervous system, including agitation, cerebral edema, coma, confusion, dizziness, headache, cranial hemorrhage, lethargy and seizures.

  • Reye's syndrome

  • Musculoskeletal, including rhabdomyolysis.

  • Respiratory, including hyperpnea, pulmonary edema, and tachypnea.

  • Endocrine, including hypoglycemia and hyperglycemia.

  • Ocular, including localized periorbital edema.

Wikipedia does a reasonable job here too, explaining more of the background.

Now that you are totally scared off from aspirin, please try to remember that these are generally either low risk or minor. The benefits of aspirin for occasional use, or where the stroke/heart risks are heavy, is probably warranted. However, these are serious considerations before popping them every day just for their prophylactic effects on Alzheimer's.


Depends on what you consider to be health benefits. I will address the question about heart attacks. Lots of medical sites and media outlets report the wonders of daily aspirin. But, in medicine, you can't claim the benefit unless you also assume the risk. It is all about risk to benefit ratios and frankly most doctors are too busy to do a complete review to determine if aspirin really is preventive of heart attack. The problem is aspirin can also cause you to have a hemorrhagic stroke (bleed in your brain) or exsanguinate or bleed to death from an ulcer. Doctors know this and good ones worry about it. So, they do a risk assessment (or should) to determine your risk of having a heart attack over the next 10 years. http://heart.arizona.edu/heart-health/prevent-heart-attacks/risks

14-16 - High risk (15-19 percent) - You stand a good chance of having a first heart attack before you are 55, if male, and 65, if female. If you have already had a heart attack, you are at high risk for a repeat performance.

Primary prevention means preventing the FIRST heart attack. There is very little evidence that daily aspirin will prevent your initial heart attack and the little possible benefit is at the risk of a head bleed stroke which has a very high mortality rate.

Currently, the worthwhile net clinical benefit of giving aspirin to healthy individuals is made difficult to assess by the imprecision of estimates of benefits and risks, especially for rare events, such as intracranial hemorrhage, and by the difficulty of weighing ischemic versus bleeding events. In the setting of secondary cardiovascular prevention on the contrary, the benefit of treatment (saving major cardiovascular events) is clearly superior to the risk (inducing major bleeding). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4669607/

However, if you are also a diabetic there may be some benefit at medium risk of first heart attack: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2875463/

Head and GI bleeds are horrible with very high rates of mortality. The suggestion to use aspirin as primary prevention is best determined by a qualified cardiologist as this site has no means of accessing or even generalizing risks. Here is a great site that offers several scenarios for when to take or not take aspirin. As you can see, daaily aspirin isn't as healthy as the media may suggest: http://www.health.harvard.edu/heart-health/new-guidelines-refine-aspirin-prescription I'd suggest get a cardiac workup to be safe

  • 1
    This is perhaps another instance where the interests of doctors and patients aren't exactly in alignment. To a doctor, success is (simplistically) a living patient. To the patient, it's much more often having a life that's worth living. So if aspirin reduces the risk of chronic conditions like heart failure & cancer at the cost of an equal increase in the risk of sudden death from other conditions, that's a tossup to the doctor, but a win to a lot of patients.
    – jamesqf
    Feb 2, 2017 at 3:23
  • I take Ibuprofen daily for arthritis even though I'm aware of its significant side effects including kidney failure. I personally provided care for a woman who required dialysis as the result of ibuprofen. niddk.nih.gov/health-information/kidney-disease/…. So, do I not use Ibuprofen? No, I assume the risk but am aware of its side effects. I may lose my gamble but may also deter Alzheimer's scientificamerican.com/article/…. You are the ultimate gatekeeper of your health not the doctor. Feb 2, 2017 at 12:38

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .