Aspirin is a common drug for relieving minor aches, pains, and fevers. People also use it as an anti-inflammatory or a blood thinner.

People can buy aspirin over the counter without a prescription. Everyday uses include relieving headache, reducing swelling, and reducing a fever.

Taken daily, aspirin can lower the risk of cardiovascular events, such as a heart attack or stroke, in people with a high risk. Doctors may administer aspirin immediately after a heart attack to prevent further clots and heart tissue death.

This article provides an overview of aspirin, including its uses, risks, interactions, and possible side effects.

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Aspirin is a nonsteroidal anti-inflammatory drug (NSAID). It was the first of this class of drug to be discovered.

Aspirin contains salicylate, a compound found in plants such as the willow tree and myrtle. Its use was first recorded around 4,000 years ago.

Hippocrates used willow bark for relieving pain and fevers, and some people still use willow bark as a natural remedy for headaches and minor pain.

NSAIDs are a class of drug with the following effects:

  • relieving pain
  • reducing fever
  • lowering inflammation, in higher doses

These drugs are not steroids. Steroids often have similar benefits to NSAIDs, but they are not appropriate for everyone and can have unwanted side effects.

As analgesics, NSAIDs tend to be non-narcotic. This means that they do not cause insensibility or a stupor.

Aspirin is a trademark owned by the German pharmaceutical company Bayer. The generic term for aspirin is acetylsalicylic acid.

Aspirin has many uses, including relieving pain and swelling, managing various conditions, and reducing the risk of cardiovascular events in people with a high risk.

Below, we describe these uses in more details.

Pain and swelling

Aspirin can relieve mild to moderate pain, swelling, or both associated with many health issues, such as:

For severe pain, a doctor may recommend using aspirin alongside another drug, such as an opioid pain reliever or another NSAID.

Preventing cardiovascular events

The daily use of low-dose aspirin can lower the risk of cardiovascular events in some people — it is not safe for everyone. The Food and Drug Administration (FDA) recommend only using aspirin in this way under the supervision of a doctor.

In people with a high risk of cardiovascular events, low-dose aspirin can reduce the risk by preventing blood clots from forming.

A doctor may recommend daily low-dose aspirin for people who :

  • have a heart or blood vessel disease
  • have evidence of poor blood flow to the brain
  • have high blood cholesterol
  • have high blood pressure, or hypertension
  • have diabetes
  • smoke

However, for people without these issues, the risks of long-term aspirin use can outweigh the benefits.

The 2016 recommendations from the United States Preventive Services Task Force say that adults aged 50–59 may take aspirin daily to prevent colorectal cancer, as well as cardiovascular disease. However, this guidance only applies to adults in the age range who:

  • have at least a 10% 10-year risk of cardiovascular disease
  • do not have a high risk of bleeding
  • have a life expectancy of at least 10 years
  • are willing to take a daily low dose for at least 10 years

Treating coronary events

Doctors may administer aspirin immediately after a heart attack, stroke, or another cardiovascular event to prevent further clot formation and cardiac tissue death.

Aspirin can also be part of a treatment plan for people who have recently had:

Other uses

Aspirin can also help treat pain and swelling associated with the following chronic health conditions:

Doctors may recommend low-dose aspirin to people:

  • with retinal damage, also called retinopathy
  • who have had diabetes for more than 10 years
  • who are taking antihypertensive medications
  • with a risk of colorectal cancer

Doctors do not usually recommend aspirin for people under 18.

This is because it can increase the risk of a serious condition called Reye’s syndrome, which can appear after a viral infection such as a cold, the flu, or chickenpox. Reye’s syndrome can lead to permanent brain injury or death.

However, a clinician may prescribe aspirin to a child under supervision if they have Kawasaki disease or to prevent blood clots from forming after heart surgery.

For children, doctors usually recommend acetaminophen (Tylenol) or ibuprofen (Advil), in appropriate doses, instead of aspirin.

People with the following conditions should be cautious about taking aspirin, and should only do so if a doctor recommends it:

Under a doctor’s supervision, people who are pregnant or breastfeeding may take low-dose aspirin. Doctors usually do not recommend high-dose aspirin during pregnancy.

Anyone with a known allergy to aspirin or any other NSAID, such as ibuprofen, should avoid these drugs.

Doctors do not administer aspirin during a stroke because not all strokes are caused by blood clots. In some cases, aspirin could make a stroke worse.

Also, anyone who drinks alcohol regularly or is undergoing dental or surgical treatment, however small, should ask a doctor before taking aspirin.

An interaction may involve one medication making another less effective or the combination being dangerous.

Aspirin can interact with many drugs. Some of these include:

  • Anti-inflammatory painkillers: Examples include such as diclofenac, ibuprofen, and naproxen. Combined with aspirin, these types of drugs can increase the risk of stomach bleeding.
  • Selective serotonin reuptake inhibitors and other antidepressants: Examples include citalopram, fluoxetine, paroxetine, venlafaxine, and sertraline. In combination with aspirin, any of these can increase the risk of bleeding.
  • Warfarin: In combination with this blood thinner, aspirin can reduce the drug’s anticoagulant effects and increase the risk of bleeding. There are situations, however, when this combination may be beneficial.
  • Methotrexate: In combination with this drug, used in the treatment of cancer and some autoimmune diseases, aspirin can the drug harder to eliminate, potentially resulting in levels of methotrexate that are toxic.

For a more complete list of drug interactions, check with the National Institute for Health and Care and Excellence.

The most common side effects of aspirin are:

The following adverse effects are less common:

  • worsening asthma symptoms
  • vomiting
  • stomach inflammation
  • stomach bleeding
  • bruising

Aspirin can also have very serious side effects, such as bleeding in the brain or stomach or kidney failure. A rare side effect of daily low-dose aspirin is hemorrhagic stroke.

Aspirin can help prevent and treat a range of health issues, but people under 18 should not take it without medical guidance.

Aspirin is available over the counter or by prescription. Always follow the instructions on the label or a doctor’s guidance. This is especially crucial for people who may be more likely to experience adverse effects.

Aspirin is not safe for everyone, especially in a daily dosage. Other options for mild pain relief include other NSAIDs, such as ibuprofen, and acetaminophen.

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