Most runners have heard the sage advice that taking anti-inflammatories like ibuprofen before or after running to manage pain and reduce muscle soreness is not a good idea. These medications can mask pain, which can potentially increase the risk of injury, or allow you to run through a niggle that requires rest.
Anti-inflammatory medications can also potentially compromise recovery, because post-exercise inflammation is an important part of the recovery process.
However, when it comes to taking aspirin before running, the advice shifts somewhat. In fact, some doctors actually encourage runners to take aspirin when running.
To learn more about aspirin and running performance, we spoke to Dr. Allan Stewart, MD, FACS, FACC, and Cardiologist and the Medical Director of Cardiovascular Surgery at HCA East Florida.
In this guide, we will look at:
- What is Aspirin and What Does It Do In the Body?
- What Are the Potential Benefits of Taking Aspirin Before Running?
- What Are the Potential Risks of Taking Aspirin Before Running?
- What Are the Potential Benefits of Taking Aspirin After Running?
- What Are the Potential Risks of Taking Aspirin After Running?
- Aspirin And Running Performance
- Who Should Consider Taking Aspirin Before Running?
- The Takeaway: Aspirin and Running Performance
Letโs get started!

What is Aspirin and What Does It Do In the Body?
Aspirin has been so ubiquitous in pharmacies and households for common use for so many decades now that we rarely even think about what it is or its long history of use.
Aspirin, which is chemically referred to as acetylsalicylic acid, was first created by chemist Felix Hoffman (who was working for Bauer at the time) in Germany in 1897.
โIt is actually a chemical modification of a homeopathic substance called salicylic acid, which is found in tree bark, as well as various grains,โ explains Dr. Stewart.
Aspirin belongs to a class of medicines known as NSAIDS, or non-steroidal anti-inflammatory drugs, which also includes medicines like ibuprofen and naproxen sodium.
โIts main effect is to block the production of a substance called prostaglandin by interfering with an enzyme called cyclooxygenase, or COX, says Dr. Stewart. โThere are three COX enzymes in the body: one is involved in producing prostaglandins involved in inflammation, the second in protecting the lining of the stomach, and the third is involved with developing fever.โ
Dr. Stewart says that aspirin can effectively block all three COX enzymes, which is why it has several benefits and applications, including its use in the prevention of heart attacks and strokes, the prevention of blood clots in patients who have undergone cardiac procedures, and to reduce fevers and pain.

What Are the Potential Benefits of Taking Aspirin Before Running?
So, why do some runners take aspirin before running? Is there an association between aspirin and running performance?
Dr. Stewart says that the primary demographic and use of taking aspirin before running centers around older runners seeking its blood-thinning effects.
โA few studies found that markers of hypercoagulopathy and platelet activation (thickened or sticky blood) is higher in runners over forty (male more than female). This hypercoagulopathy is strongly predictive of a cardiac event during vigorous exercise,โ explains Dr. Stewart.
In fact, Dr. Stewart says the major cause of death in marathon runners over the age of 40 years old is a heart attack caused by a new clot formed in a major coronary artery.
โTaking low dose aspirin (81mg), lowers the risk of heart attack by as much as 44% in various reports. These findings led to the recommendation that all male marathon runners over 40 years old should take pre-race aspirin.โ

Interestingly, the recommendations for women are somewhat different because, as Dr. Stewart notes, women are generally protected from premature coronary disease until after menopause.
After menopause, however, he says the risk of coronary disease rapidly catches up to that of age-matched men.
Unfortunately, there are few studies looking at aspirin for female runners, so there arenโt really guidelines or recommendations in place.
โMy advice would be that in the absence of any gastrointestinal problems, such as reflux or ulcers, 81mg is well tolerated,โ says Dr. Stewart. โEven if only modest protection is provided, the benefit still outweighs the risk.โ
What Are the Potential Risks of Taking Aspirin Before Running?
Of course, aspirin is a drug so thereโs always going to be at least some physiological effects of taking it.
Therefore, itโs probably a good idea to think about whether you need to take aspirin before running as well as the potential effects of aspirin and running performance.
If youโre a male runner over the age of 40, Dr. Stewart says there are very few risks associated with taking aspirin before running as long as you donโt have gastrointestinal problems and you take a low-dose (81mg or less, as 325 mg can cause irritation).
However, having food and water with aspirin is important.
โLong runs, such as 10K, half-marathon, full marathon, etc., are often undertaken without proper hydration or nutrition. Aspirin on an empty stomach can cause reflux, an unpleasant feeling, and in rare cases ulceration,โ says Dr. Stewart. โItโs important to take the aspirin with a glass of water and to properly hydrate throughout the run.โ

In addition to runners with GI disorders, runners with bleeding disorders or who take other medicines that affect coagulation or blood viscosity should consult their doctor before taking aspirin for running.
โOne additional theoretic risk is that aspirin blunts our bodyโs perception of pain. This can allow a runner to persist in exercise and worsen an injury, due to lack of awareness,โ warns Dr. Stewart. โWith an 81 mg dose, however, it is unlikely to have much of an impact.โ
What Are the Potential Benefits of Taking Aspirin After Running?
The majority of studies involving aspirin and endurance exercise center around taking aspirin before a workout for its potential cardio-protective benefits, but some runners seeking pain relief choose to take aspirin after a run.
However, Dr. Stewart says these benefits are only temporary, and shouldnโt be the focus when taking aspirin for running.
โThe cardio-protective effects of aspirin only exist if taken prior to the run. Of course, if a runner is experiencing chest pain during or afterwards, aspirin can be life-saving. In such a case, it is best consumed by dissolving under the tongue.โ
He notes that for pain and fever reduction, an ice bath, topical ice, and hydration with cold electrolyte solutions are much better choices than aspirin.

What Are the Potential Risks of Taking Aspirin After Running?
Although runners might want to grab a bottle of aspirin after a run to ease muscle soreness, taking aspirin after running for muscle pain is actually counterproductive.
Aspirin is an anti-inflammatory drug, and although inflammation is often vilified, thereโs actually an important physiological effect of inflammation.
According to Dr. Stewart, โInflammation creates a signal for the body to deploy its resources to heal, repair, and adapt. Blunting this signal may lead to inadequate recovery from a strenuous workout.โ
It is important to note that most of the research surrounding the potential risks or drawbacks of taking aspirin on muscle recovery are associated with higher doses (325mg of aspirin), rather than low-dose (81mg) aspirin recommended before running.
Dr. Stewart adds that long-term use of high dose aspirin has been shown to reduce muscle growth and lead to a decrease in muscular strength.

Aspirin And Running Performance
In terms of the effects of aspirin and running performance, evidence suggests that taking aspirin before submaximal and maximal-intensity exercise does not significantly affect athletic performance.
Who Should Consider Taking Aspirin Before Running?
Given the research and the potential cardio-protective effects of aspirin, Dr. Stewart says the following runners can potentially benefit from taking aspirin before running:
- Runners who have a personal or a strong family history of coronary disease.
- Habitual runners embarking on long distance runs should take 81 mg, unless there is a contraindication.
- Men over 40 and post-menopausal women will have greater protection from heart attack or stroke.

The International Marathon Medical Directors Association (IMMDA) has recommended pre-race aspirin for males over the age of 40 years with approval by their physicians after considering risks such as gastrointestinal bleeding or allergy.
Remember, if you have gastrointestinal bleeding, take blood thinners or other anti-inflammatories, or have other medical conditions that affect bleeding should not take aspirin before running unless they have discussed it with their physician.
The Takeaway: Aspirin and Running Performance
Dr. Stewart says that while aspirin is an important medication for the prevention of heart attacks with exercise, taking aspirin before running does not eliminate the need to use common sense and listen to your body.
โAlways wear a heart rate monitor and exercise with the proper intensity levels. If you feel poorly, slow down,โ he advises. In the heat of the summer, continuously hydrate, not with pure water, but with balanced electrolytes solutions.โ
And, when it comes to taking aspirin after running for sore muscles, Dr. Stewart says topical ice, ice baths, topical analgesics like Tiger Balm, and post-exercise protein shakes are much better recovery solutions than masking pain with aspirin.
For information on protein for runners and how it can assist with recovery, take a look at our guide: Protein For Runners: Explained.
