Aspirin In the Bloodstream: How Long Will It Last? (2024)

Aspirin is a nonsteroidal anti-inflammatory drug (NSAID) for pain relief. It may also be taken for its antiplatelet effects as a blood thinning medication, which can help treat and prevent heart attack and stroke. It is also referred to as acetylsalicylic acid (ASA) and salicylic acid.

Aspirin has a very short half-life, meaning it is cleared quickly from the body. How long aspirin stays in your system can vary based on whether or not the tablet is coated, the dose taken, and the dosage form.

Aspirin will generally stay in your system for up to 10 days.

This article will discuss how quickly and for how long aspirin works, guidance on using it safely, potential side effects, and more.

Aspirin In the Bloodstream: How Long Will It Last? (1)

What Is Aspirin?

Aspirin is an NSAID. It is taken most commonly to:

  • Relieve pain
  • Reduce fever
  • Reduce the risk of heart attack and stroke

Aspirin is available in several different dosage forms and can be administered orally (by mouth), rectally (by rectum), and intravenously (into the veins, or IV).

Immediate-release formulations are taken for:

  • Pain and fever relief
  • Those who have undergone revascularization procedures (such as a coronary artery bypass graft)
  • Risk reduction in individuals who have experienced a heart attack or stroke

Extended-release formulations are approved for:

  • Risk reduction in individuals who have experienced a stroke
  • Risk reduction in those who have stable ischemic heart disease

Aspirin is available in the following oral dosage forms and doses:

  • Tablet: 325 milligrams (mg), 500 mg
  • Delayed-release tablets: 81 mg, 325 mg, 500 mg, 650 mg
  • Chewable tablets: 81 mg

Aspirin is also available as an enteric-coated tablet. Enteric-coated tablets are absorbed in the small intestine, whereas regular aspirin is absorbed in the stomach. Enteric-coated aspirin is associated with delayed absorption and onset of action.

Low-dose aspirin (81 mg) is often called baby aspirin but should not be taken by babies. Aspirin should not be taken by individuals under 12 years of age.

Aspirin should not be taken by children under 18 years of age who have or recently had chickenpox, the flu, or another viral illness due to the risk of Reye's syndrome.

Off-Label Uses

A medication's use is off-label when it is prescribed for a purpose or at a dose other than its U.S. Food and Drug Administration (FDA)-approved use.

Aspirin has been taken off-label in pregnancy to prevent:

  • Preeclampsia in those who have high-risk conditions
  • Fetal growth restriction
  • Miscarriage in antiphospholipid antibody syndrome (APS)

Other off-label uses for aspirin include:

  • Colorectal cancer risk reduction
  • Migraine
  • Pericarditis
  • Heart disease prevention

OTC vs. Rx Aspirin

Aspirin is available both over the counter (OTC) and by prescription. Getting a prescription for aspirin rather than buying it as an OTC product can help save you money if your insurance covers it.

Your healthcare provider may prescribe aspirin if it is intended to be taken daily.

There are currently no brand-name, prescription-only aspirin formulations.

Durlaza was previously available as a prescription-only brand of extended-release aspirin.

It was taken to reduce the risk of death and heart attack in those with chronic coronary artery disease (CAD) and to reduce the risk of death and recurrent stroke in those who have had an ischemic stroke or a transient ischemic attack (TIA) but was removed from the market and is no longer available.

There are several different brands of aspirin available without a prescription.

OTC Aspirin Brand Names

Some brand names of over-the-counter (OTC) aspirin include:

  • Ascriptin
  • Bayer
  • Bufferin
  • Ecotrin
  • Entercote
  • Halfprin
  • Ninoprin

How Does Aspirin Work?

Aspirin works to relieve pain and fever by blocking an enzyme called cyclooxygenase (COX). COX plays a major role in producing prostaglandins, which act as messengers in our body that tell our brain when something is wrong, such as when pain, inflammation, or fever are present.

The reduced COX activity minimizes these sensations.

Aspirin also works as a blood thinner by reducing prostaglandin production, allowing blood to flow more smoothly and preventing blood clots.

At low doses, aspirin inhibits COX-1 only. At higher doses, aspirin inhibits COX-1 and COX-2. This is why different doses may be taken for different purposes.

Aspirin belongs to a family of medications known as salicylates that aim to reduce inflammation. Salicylate is a substance found in willow tree bark. The medications in this family have varying chemical makeup but work similarly in the body and are taken for the same purpose.

How Long Does Aspirin Stay in Your System?

Typically, aspirin will stay in your system for up to 10 days. This can vary based on drug-specific factors such as dose, dosage form, and whether it has enteric tablet coating.

How long aspirin stays in your system differs from the actual experienced effects of the medication.

A drug's half-life refers to the time it takes for the active ingredient to be reduced by half in the body. The half-life of aspirin is 20 minutes.

Aspirin has a dose-dependent effect that determines the mechanism by which the drug will work in the bloodstream.

Developing a tolerance to aspirin, even with long-term use, is not common.

How Quickly Will It Work?

Regular aspirin usually begins working within minutes of taking it when taken as an antiplatelet medication. Enteric-coated aspirin takes longer but must be chewed to exhibit the same rapid onset.

When taking aspirin for pain relief, you should begin to feel better within 30 minutes of taking the medication.

Aspirin is effective for four to six hours.

How Effective Is Aspirin?

Research suggests that aspirin can benefit those experiencing tension headaches and muscle aches.

NSAIDs are a common class of medication taken for autoimmune disorders. Other NSAIDs are taken more commonly than aspirin for rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) due to the safety profile of the medication.

Aspirin is recommended for pregnant people with SLE to prevent blood clots and miscarriage. Low-dose aspirin may also be taken by non-pregnant people with SLE to prevent blood clots.

Side Effects and Precautions

The most common side effect associated with aspirin use is gastrointestinal (GI) upset, which may cause symptoms such as nausea, vomiting, stomach pain, and heartburn.

Severe side effects associated with aspirin use include:

  • Allergic reaction: symptoms may include hives, facial swelling, and wheezing
  • Reye’s syndrome: symptoms may include vomiting, fatigue, personality changes, and confusion
  • Stomach bleed: symptoms may include dark/bloody stools, vomiting blood, and stomach pain

Aspirin Toxicity

Aspirin toxicity can occur if more than the recommended dose is taken, and high levels can be life-threatening.

Symptoms of aspirin toxicity may include:

  • Ringing in the ears
  • Dizziness
  • Nausea
  • Vomiting
  • Lack of energy

Severe cases may cause lab abnormalities, seizures, coma, and brain swelling. Avoid aspirin toxicity by only taking it as directed or prescribed. Seek medical attention if symptoms occur.

How to Safely Take Aspirin

You should never double your dose while taking aspirin, but you may take a missed dose as soon as you remember. If it's almost time for your next dose, skip the missed dose and continue your usual schedule.

Aspirin should be stored in a secure, dry area at room temperature. It should be kept out of the sight and reach of children. Do not store it in the bathroom or the car.

Drinking alcohol while taking aspirin can increase your risk of stomach issues. Avoid excessive alcohol intake (more than three drinks per day) while taking aspirin.

Extended-release tablets should not be broken, crushed, or chewed.

Use in Specific Populations

People with the following preexisting conditions should avoid taking aspirin unless otherwise instructed by a healthcare provider:

  • NSAID allergy
  • Asthma
  • GI issues such as peptic ulcer disease (PUD) and gastritis
  • Glucose-6-phosphate dehydrogenase (G6PD) deficiency
  • Platelet and bleeding disorders
  • Dehydration
  • Heavy alcohol use
  • Liver failure

Children under 18 years of age who are recovering from chickenpox, flu, or other viral illness should not take aspirin.

People 65 years and older should avoid chronic aspirin use at doses higher than 325 mg due to an increased risk of GI bleeding, PUD, and other side effects.

Aspirin can be taken at low doses for pregnancy-related conditions but should otherwise be avoided after the first 20 weeks of pregnancy. Low-dose aspirin may be taken while breastfeeding, but other non-opioid pain medications are preferable.

Avoid taking aspirin with the following medications due to their potential to cause adverse effects and limit their effectiveness:

  • Other NSAIDs (such as ibuprofen)
  • Gout medication (such as probenecid)
  • Blood-thinning medications (such as warfarin)

Alternative Treatment Options

Some non-pharmaceutical treatment options for headaches and muscle aches include:

  • Acupuncture
  • Electrical stimulation
  • Massage therapy
  • Meditation
  • Physical therapy
  • Relaxation therapy

Some non-pharmaceutical treatment options for relieving menstrual period-related symptoms include:

  • Exercise
  • Rest
  • Diet changes
  • Cold and heat therapy

Comparing Different Medicines for Period Cramps: What’s Strongest?


Aspirin is an NSAID that is taken for both its pain relief and antiplatelet effects. It is available in prescription and OTC in several different dosage forms. Aspirin should be avoided in young children and older adults due to potential side effects.

In most cases, aspirin will stay in your system for up to 10 days. However, this can vary based on drug-specific factors such as dose, dosage form, and the presence of tablet coating.

Lower doses of aspirin may be taken long-term, whereas higher doses should only be taken short-term or as directed by a healthcare provider. Avoid taking aspirin for longer than 10 days without consulting with your provider.

Aspirin In the Bloodstream: How Long Will It Last? (2024)


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