An aspirin overdose can occur after a single large dose (this is called an acute overdose) or develop gradually after taking lower doses for a long time (this is called a chronic overdose). An acute aspirin overdose may be accidental or intentional.

A toxic dose of aspirin for a human adult is considered to be 200 to 300 milligrams per kilogram of body weight (works out to be 13,600 to 20,400mg of aspirin for a person who weighs 68 kg [approximately 150 pounds]). A dose of 500 milligrams per kilogram of body weight (34,000mg for a 68kg person) is considered a potentially lethal dose of aspirin, and could result in death.

In older adults or people with malfunctioning kidneys taking regular medium to high-dose aspirin (325-650mg every 4 to 6 hours), dehydration or hot weather can heighten the risk of chronic overdose. It’s important to discuss your use of aspirin with your doctor, as you may have factors that increase your risk of overdose. The low dosage of aspirin recommended for people to reduce their risk of a heart attack or stroke (1 baby aspirin or ½ of an adult aspirin) is too small to cause aspirin poisoning even when taken for a long time.

Toxic and lethal doses for children are much lower. Children under the age of 16 are also at risk of Reye syndrome (a rare and sometimes fatal disorder associated with aspirin use that can cause swelling in the liver or brain), even with usual dosages of aspirin, which is why aspirin is generally not recommended in children and teenagers. Make sure to keep aspirin out of sight and away from children.

What are the symptoms of an aspirin overdose?

If a single large toxic dose of aspirin has been taken, the first symptoms are usually:

• Nausea and vomiting
• Rapid or deep breathing
• Ringing in the ears (tinnitus)
• Sweating.

If the poisoning is severe, light-headedness, a fever, drowsiness, blurry vision, agitation, confusion, seizures, difficulty breathing, or kidney failure may develop.

In gradual aspirin poisoning, symptoms can take days or weeks to develop and may include:

• Drowsiness or light headedness
• Dehydration
• Low blood pressure
• Fast heart rate
• Subtle confusion
• Hallucinations.

Rapid breathing, shortness of breath, fever, fluid in the lungs (pulmonary edema), changes in laboratory values (such as a low oxygen level in the blood or a buildup of lactic acid in the blood), seizures, and brain swelling can develop.

When should you seek medical assistance for an aspirin overdose?

If you or someone around you has taken a potentially toxic dose of aspirin, or you suspect an aspirin overdose for another reason, you must seek emergency medical care as soon as possible or call your local emergency number. If you are in the United States, call 911 or contact the national, toll-free Poison Help hotline at 1-800-222-1222.

You can call the Poison Help hotline in the event of a potential aspirin overdose, even if it is not an emergency. Poison control experts can answer any questions you may have and provide advice on how to proceed.

How is aspirin poisoning diagnosed?

The diagnosis is based on blood tests, the person's symptoms, and their history of aspirin use.

How is aspirin poisoning treated?

Treatment involves giving activated charcoal by mouth or stomach tube, giving fluids and bicarbonate by vein, and, for severe poisoning, undergoing hemodialysis - this uses an artificial kidney to filter out the aspirin.

What is aspirin?

Aspirin, also known as acetylsalicylic acid, is a pain-relieving drug found in many prescription and over-the-counter formulations. It reduces inflammation and can help reduce symptoms such as fever, pain, and swelling. At very low doses it can reduce the risk of blood clots forming. You may have taken aspirin to reduce the pain of a headache or toothache, relieve menstrual pain or deal with cold or flu symptoms, but like every drug, it comes with benefits as well as risks.

• Aspirin can be harmful and lead to bleeding in the stomach or brain, or even kidney failure or death.
• The regular use of aspirin is something you’ll want to discuss with your doctor.

Here’s why you might take aspirin:

• In its over-the-counter form, aspirin may be used to treat fever and mild to moderate pain and may be recommended daily to help prevent heart attacks or strokes in certain high-risk groups.
• Prescription aspirin can provide long-acting symptom relief to patients with certain kinds of autoimmune diseases, such as rheumatoid arthritis and lupus.

But, it’s important to note that children under 16 should never take aspirin, and caution is warranted for young adults, too. Aspirin comes with a risk of Reye syndrome, especially in children who took it while recovering from viral infections like chickenpox or flu. This rare but serious condition causes sudden damage to the brain and problems with the liver. Because of this risk, aspirin is not a recommended medication for routine treatment in children or young adults.

What is a standard dose of aspirin?

The proper dosage of aspirin depends on why you are taking aspirin, the type of aspirin you are taking and how well it is working for you.

Aspirin comes in various forms, including:

• Regular tablets
• Delayed-release tablets
• Extended-release tablets
• Chewable tablets
• Rectal suppositories.

Dosing may vary. Typical strengths you might purchase over the counter include:

• 81 mg tablets or chewables are sometimes referred to as “baby aspirin” or “low-dose aspirin,” as this is the lowest dose available over the counter
• 325 mg tablets may be labeled "regular strength"
• 500 mg aspirin tablets are considered "extra strength."

Other strengths may include:

• 162.5 mg extended-release daily capsules may be prescribed
• 600 mg dosing may be found in rectal suppositories (as well as other lower strengths)
• 650 mg dosing may be available as delayed-release tablets (as well as other lower strengths).

According to the label: for pain and fever, adults and children over age 12 may take aspirin every 4 to 6 hours, but your doctor may recommend other pain relievers instead, so it’s a good idea to check. For the prevention of heart attack or stroke, once-daily low-dose aspirin may be advised by your doctor and should only be done under the advice of a physician.

• Take aspirin exactly as directed.
• Talk to your doctor if you have any questions or concerns about the proper aspirin dose for you.