Aspirin is a widely available over-the-counter medication that shows substantial effects at promoting survival and reducing risk of many types of cancer, plus reducing inflammation and managing pain due to inflammation.

Safety and precautions

All nonsteroidal anti-inflammatory drugs (NSAIDs) including aspirin can have serious, even life-threatening side effects. Use them only under medical supervision.

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of substantially increased all-cause mortalitydeath, or the death rate in a population; cancer studies often report all-cause mortality (death from any cause) and cancer-specific mortality (death due to the cancer under investigation) among people with postmenopausal hormone receptor-positive breast cancer using low-dose aspirin (81 mg or less)

  • Substantially worse (67% higher) all-cause mortality among people with postmenopausal hormone receptor-positive breast cancer using low-dose aspirin (81 mg or less) compared to no use in a large observational study1Strasser-Weippl K, Higgins MJ et al. Effects of celecoxib and low-dose aspirin on outcomes in adjuvant aromatase inhibitor-treated patients: CCTG MA.27. Journal of the National Cancer Institute. 2018 Sep 1;110(9):1003-1008.

Extreme caution is advised for people with low body weight, as shown in a pooled analysis of 10 very large RCTsrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects:2Rothwell PM, Cook NR et al. Effects of aspirin on risks of vascular events and cancer according to bodyweight and dose: analysis of individual patient data from randomised trials. Lancet. 2018 Aug 4;392(10145):387-399. 

  • Higher risk of sudden death among people using aspirin with low body weight for the dose received 
  • 52% higher all-cause mortality among people weighing less than 50 kg (110 pounds) receiving 75–100 mg of aspirin
  • 20% higher 3-year risk of cancer among people aged 70 years or older using aspirin, especially those weighing less than 70 kg (154 pounds)

One study found a trend toward higher risk of cancer progression among elderly patients with stage 3 or 4 cancers using aspirin.3McNeil JJ, Gibbs P et al. Effect of aspirin on cancer incidence and mortality in older adults. Journal of the National Cancer Institute. 2020;djaa114.

Cancer risk

Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of higher risk of recurrent advanced adenomas and/or 2 or more adenomas after colorectal adenoma surgery among people using aspirin 4 or more days/week and using vitamin D3

  • Higher risk of recurrent advanced adenomas and/or 2 or more adenomas after colorectal adenoma surgery among people using aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) 4 or more days/week and using 1000 IU/day vitamin D3 compared to those with less frequent NSAID use in a large RCTrandomized controlled trial, a study design in which people are randomly assigned to either an experimental group or a control group to compare the outcomes from different treatments; an RCT is considered a strong design for determining a therapy’s effects4Calderwood AH, Baron JA, et al. No evidence for posttreatment effects of vitamin D and calcium supplementation on risk of colorectal adenomas in a randomized trial. Cancer Prevention Research. 2019 May;12(5):295-304.

Side effects or adverse events

Aspirin can have many side effects, some potentially very serious. For this reason, we highly recommend having a physician monitor your use and guide you in looking for indications of any serious conditions.

Common side effects:5Aspirin Tablet Side Effects by Likelihood and Severity. Web MD. Viewed February 8, 2021; Cook NR, Lee IM, Zhang SM, Moorthy MV, Buring JE. Alternate-day, low-dose aspirin and cancer risk: long-term observational follow-up of a randomized trial. Annals of Internal Medicine. 2013 Jul 16;159(2):77-85.

  • Allergic reactions, including potentially serious reactions
  • Bleeding, including bleeding of the stomach or intestines or within the skull
  • Drowsiness
  • Excess stomach acid secretion
  • Gastrointestinal upset, nausea or ulcers (risk of ulcers is increased with alcohol use)
  • Heartburn
  • Nausea
  • Stomach cramps
  • Vomiting
  • Worsening asthma symptoms

Rare side effects:6Aspirin Tablet Side Effects by Likelihood and Severity. Web MD. Viewed February 8, 2021; McNeil JJ, Wolfe R et al, ASPREE Investigator Group. Effect of aspirin on cardiovascular events and bleeding in the healthy elderly. New England Journal of Medicine. 2018 Oct 18;379(16):1509-1518..

  • Anemia
  • Decreased appetite
  • Difficulty breathing
  • Itching
  • Liver damage and inflammation
  • Ringing in the ears
  • Skin blistering or hives

Caution is advised for people with hypertension or risk factors for gastrointestinal bleeding. One review does not advise discontinuing use of aspirin and other NSAIDs among people with cancer, but the authors recommend careful monitoring for side effects such as cardiovascular events (with COX-2 inhibitors) or gastrointestinal bleeding.7Solheim TS, Fearon KC, Blum D, Kaasa S. Non-steroidal anti-inflammatory treatment in cancer cachexia: a systematic literature review. Acta Oncologica. 2013 Jan;52(1):6-17.

Do not use (contraindications)

Allergic reactions to aspirin can be fatal. If you suspect or know you are allergic to aspirin or salicylates, do not use aspirin.

Drug interactions

The US Food and Drug Administration cautions that some nonsteroidal anti-inflammatory drugs (NSAIDs), including those in over-the-counter products such as ibuprofen and naproxen, can interfere with the antiplatelet action of low-dose aspirin used for cardioprotection.8FDA Drug Safety Communication: FDA strengthens warning that non-aspirin nonsteroidal anti-inflammatory drugs (NSAIDs) can cause heart attacks or strokes. US Food and Drug Administration. February 2, 2015. Viewed October 21, 2021. 

Aspirin can also potentially interact with blood thinners, selective serotonin reuptake inhibitors (SSRIs), other nonsteroidal anti-inflammatory drugs, various antihypertensives, methotrexate, steroids, valproic acid, ginkgo biloba, and other drugs. Be sure to mention to your physician that you are taking any of these medications before using aspirin.

Keep reading about aspirin

Authors

Nancy Hepp, MS

Lead Researcher and Program Manager
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Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher, program manager, and writer for CancerChoices. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS Lead Researcher and Program Manager

Laura Pole, RN, MSN, OCNS

Senior Clinical Consultant
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Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.

For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.

Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.

Laura Pole, RN, MSN, OCNS Senior Clinical Consultant

Reviewer

Barry D. Elson, MD

Integrative physician and CancerChoices advisor
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Barry D. Elson, MD, has been practicing and teaching integrative medicine for over 40 years. He has been the medical director of Northampton Wellness Associates, adjunct faculty for Touro University College of Medicine, medical director at Commonweal, and professor of medicine at the Pacific College of Naturopathic Medicine. He recently retired from clinical practice and has been providing freelance medical consulting. He is an avid biker, cross country skier, and sailor. He currently resides in the rolling hills of western Massachusetts.

Barry D. Elson, MD Integrative physician and CancerChoices advisor

Maria Williams

Research and Communications Consultant
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Maria Williams is a research and communications consultant who brings over 15 years’ experience in research, consumer education, and science communication to CancerChoices. She has worked primarily in public health and environmental health.

Maria Williams Research and Communications Consultant

Last update: December 1, 2022

Last full literature review: September 2021

CancerChoices provides information about integrative in cancer care, a patient-centered approach combining the best of conventional care, self care and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocial therapy, and acupuncture therapies and self-care lifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.

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