How Long Does Aspirin Stay In Your Body?

Aspirin is a common medicine for headaches, toothaches, fever, or flu-like symptoms. Moreover, the drug also helps in preventing blood clots and swelling due to arthritis.

This is probably one of the most popular drugs that you use without consulting the doctors. But you must be wondering about how many doses of aspirin you should take? Or how long does aspirin stay in your system?

Let’s check out the answers here.

How Does Aspirin Work?

Aspirin belongs to the group of non-steroidal anti-inflammatory drugs (NSAIDs). Its major functions are:


Aspirin is used to block cyclooxygenase (COX) enzymes. The enzyme increases the rate of conversion of arachidonic acid into prostaglandins and thromboxanes that trigger inflammation.

Aspirin reduces inflammation in two ways:

  • First, by reducing the synthesis of prostaglandins and thromboxanes that are pro-inflammatory.
  • When prostaglandins and thromboxanes are not produced, the arachidonic acid travels to the lipoxygenase cycle. It causes the aspirin-induced production of lipoxins. These lipoxins are also anti-inflammatory. These effects are seen as long as aspirin stays in your system.

Antipyretic (Fever Reducing)

When prostaglandins level is elevated in the brain by infection or swelling, it acts on receptors in the hypothalamus.

This interaction between prostaglandins and prostaglandin fluctuates the hypothalamic set point of body temperature and elevates your core temperature, resulting in fever. Aspirin blocks the production of these prostaglandins and reduces fever.

Prevent  Blood Clotting

Aspirin acts on the COX-1 enzyme of platelets that reduces the production of thromboxane-A2, which is an essential factor in platelets aggregation. So now, platelets cannot clump together, and blood clots are not formed.

Who Should Use Aspirin?

Aspirin is recommended to those who are suffering from:

  • Fever: Because aspirin acts as antipyretics.
  • At the risk of stroke or heart attack: Aspirin reduces blood clotting and reduces the risk of clot formation in brain and heart blood vessels.
  • Headaches, toothaches, aches, and pain: Aspirin reduces prostaglandins production in tissues that cause pain.
  • Swelling such as in arthritis: Because of reduced prostaglandin and thromboxane production, swelling subsides.

Is It Safe to Take Excedrin for Back Pain?

Aspirin is effective in acute migraine treatment. But the outcome is temporary because of the short half-life of aspirin in plasma.

How Does Aspirin Get Absorbed?

Aspirin is usually absorbed in the stomach or small intestine. Then it travels to the liver, broken down into acetylsalicylic acid. From the liver, it binds to the plasma proteins.

Aspirin comes in the form of enteric-coated and regular aspirin. People previously believed that enteric-coated aspirin is not absorbed in the stomach but the colon, so it does not increase stomach acidity that causes stomach ulcers. However, now it is proved that this concept is wrong.

how long does aspirin stay in your system

After absorption, it enters the blood and can indirectly affect the stomach and cause ulcers if taken in large amounts. But how long does aspirin stay in your system? Stay with me for the answer.

Although aspirin has salicylic acid, its effect is better than the other salicylic acid drugs on the market. Advantages of taking aspirin over other salicylate are:

  • Aspirin loosely binds the plasma proteins. So it can easily dissociate from plasma proteins in the blood and can travel to tissues. In this way, aspirin is readily available to the body tissues. However, most salicylic acids bind tightly with plasma proteins, so not available readily to tissues.
  • As aspirin is easily available to tissues, it is more effective than salicylic acid.
  • Aspirin has less irritating effects on the stomach as compared to salicylic acid.

Aspirin takes less than 60 minutes to get absorbed in blood from the stomach or small intestine. But now, you must be thinking about how long aspirin stays in your system.

Half-life of Aspirin in the Body

Aspirin, once absorbed in the body, is converted into acetylsalicylic acid. This activation of aspirin takes place in the liver.

Then, it enters into the blood plasma, from where it gets absorbed into the extracellular fluid. Once it enters the body tissues, it activates complex mechanisms in the cells. Acetylsalicylic acid is then deacetylated and excreted from the body.

In the blood plasma, the concentration of acetylsalicylic acid reaches its peak in approximately 1-2 hours of ingestion of aspirin. Multiple research has been performed on how long does aspirin takes to get out of your system. It depends on how many doses of aspirin you have taken.

When you visit a pharmacy to take aspirin and see aspirin of different potency, these questions may come to your mind: how long does 75 mg aspirin stay in your system, or how long does 325 mg aspirin stay in your system? The simple answer to this question is that it is dose-dependent.

  • The elimination half-life for low doses (100mg or less) is 2-3 hours.
  • The elimination half-life for large doses (above 100mg) is 15-30 hours.

Salicylates are excreted mostly in urine (80%) by kidneys and eliminated in small amounts in sweat, saliva, and feces. I am sure you are no longer wondering about how long does it take for one aspirin to get out of your system.

How Long Does Aspirin Take To Work?

Aspirin has a life of only 20 minutes in your plasma. It means that aspirin has only 20 minutes to perform its action in body tissues. But how long does aspirin last for pain? Well, it can affect your platelets for 10 days to reduce the pain or fever.

Platelets that are responsible for blood clotting in your body have a life of about 10 days. And 10% platelets are replaced daily in your body with new platelets. Aspirin blocks the COX-1 enzyme of platelets irreversibly. So once these enzymes block, they can never work again.

The turnover rate of platelets is 10% daily. So, it takes about 10 days for platelets to become 100% functional. But still, the clotting mechanism returns to normal if 20-30% of platelets are functioning normally. So aspirin inhibits the clotting mechanism for about 3-4 days.

How Frequently Should You Take Aspirin?

It would help if you chose the aspirin doses according to the condition you want to treat. If you take aspirin as a pain reliever, you will take aspirin of high potency 2-3 times a day.

Aspirin stays in your body for a short time. So, you have to take non-prescription aspirin of about 300mg after 4-6 hours daily as needed to reduce pain and fever. Prescription aspirin is about 2 or more times per day.

how long does aspirin stay in your system

To reduce the risk of heart attacks and stroke, one should take 75mg aspirin once a day. But stroke and heart attack patients should consult with a physician before taking It. There can be other reasons for stroke and heart attacks, along with blood clots.

Final words

Aspirin is an antipyretic, anti-inflammatory, pain reliever, and anti-coagulant. If you take it as an antipyretic and pain reliever drug, it is better to take it at recommended dosages.

But patients at risk of stroke and heart attacks due to blood clots must consult cardiologists and neurologists before taking aspirin. Because how long does aspirin stay in your system can be a vital factor in treating those issues.


How do you get aspirin out of your system?

Aspirin is usually eliminated by our kidneys, gut, sweat glands, and salivary glands. After completing its life in blood plasma, aspirin is deacetylated in the liver. The left-behind products are further degraded and detoxified in the liver.

From the liver, these waste products are eliminated mainly by the kidney (80%). But some of the waste products are also eliminated in feces by git, saliva by salivary glands, and sweat by sweat glands in the skin.

How long does aspirin thin your blood?

Aspirin is an anticoagulant drug that blocks the COX-1 enzyme of platelets permanently. This enzyme increases the rate of conversion of arachidonic acid into thromboxanes-A2. And the A2 is essential for platelet aggregation and forming blood clots.

Aspirin stays in your body for a short period, but its effects on the blood clotting mechanism are long-lasting. Aspirin can affect standard clotting mechanisms for up to 6 days. That is why surgeons usually stop patients from taking an aspirin a week ago from surgery.

What is the half-life of aspirin?

Much research is done on how long aspirin can stay in your system. After ingestion, aspirin is metabolized by the liver in acetylsalicylic acid and readily appears in the blood. This whole process takes 1-2 hours, after which aspirin is at its peak in blood.

In blood plasma, the half-life of aspirin is only 10 minutes. It means it stays only for 20 minutes in blood, after which it may either enter into tissues or eliminate out from the body.

Is it ok to take aspirin twice a day?

Aspirin dose recommendation depends on the disease or symptom you want to treat. If you have fever or swelling and want to take aspirin, you should go for high potent aspirin at least 2-3 times per day.

But if you want to reduce the risk of stroke and heart attacks due to blood clots, you should take aspirin of low potency (less than 100mg) and take one aspirin per day. But these patients should surely consult their doctors before taking aspirin. 

Dr. Afifa Amer

Dr. Afifa Amer

My name is Afifa Amer and I have done Doctor of Pharmacy. I am a registered retail pharmacist. I believe we should not stick to one specific job, so writing and educating others has always been my passion. I love to share content that improves health, fitness and well being. When I am not typing or dealing with prescriptions, I like to travel and read books. -a blog about Healthy Living