Aspirin: Uses, Side Effects, and Safe Use
Aspirin (acetylsalicylic acid) is an over-the-counter medicine that reduces pain, fever, and inflammation. It is also used at low doses to help prevent certain cardiovascular events when prescribed by a clinician. Dosing and safety depend on your age, health, and the reason for taking it.
Use aspirin only as directed on the label or by your doctor, because misuse or combining it with other medicines can cause serious bleeding. A pharmacist or doctor can help confirm whether aspirin is appropriate for you.
Key facts at a glance
- ATC
- N02BA01
- Generic
- Aspirin
- Class
- antiplatelet
- Brands
- Bayer, Ecotrin
- Availability
- behind_counter
- Pregnancy
- D
- Lactation
- caution
- Half-life (h)
- 0.5
- Onset (min)
- 30
- Duration (h)
- 7
- Routes
- oral
- Forms
- tablet
- Regions
- CN, US, EU, JP
- Monitoring
- coagulation, gastrointestinal
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 500mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 250mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 400mg daily
- Maximum
- consult physician
- Frequency
- once daily
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
7 groupspregnancy
first trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks; low-dose aspirin may be considered in specific high-risk cases under medical supervision
regular fetal monitoring and ultrasound assessments
Use of this medication in this population requires careful consideration of risks and benefits.
pregnancy
third trimesteravoid completely
do not use during third trimester due to risk of premature closure of ductus arteriosus in fetus and bleeding complications
fetal echocardiography if exposed
Use of this medication in this population requires careful consideration of risks and benefits.
lactation
breastfeedingavoid
do not use during breastfeeding; aspirin passes into breast milk and may cause platelet dysfunction and bleeding risk in infant
monitor infant for signs of bleeding or bruising
Use of this medication in this population requires careful consideration of risks and benefits.
pediatric_age
children adolescentsavoid completely in children under 16 years with viral infections
do not use in children or teenagers recovering from viral illnesses (especially influenza or chickenpox) due to risk of Reye's syndrome
watch for signs of encephalopathy, vomiting, and liver dysfunction
Use of this medication in this population requires careful consideration of risks and benefits.
geriatric
elderly over 65use lowest effective dose; consider dose reduction
use with caution due to increased risk of GI bleeding, renal impairment, and drug interactions; monitor for signs of bleeding
regular renal function tests, CBC monitoring, and GI symptom assessment
Use with caution and monitor for adverse effects.
renal_impairment
mild to moderatedose reduction may be required; avoid in severe impairment
use with caution; aspirin is renally excreted and may accumulate in renal impairment; avoid in severe renal failure
monitor renal function regularly (creatinine clearance, serum creatinine)
Use with caution and monitor for adverse effects.
hepatic_impairment
mild to moderatedose reduction recommended; avoid in severe hepatic impairment
use with caution; aspirin is metabolized in the liver; avoid in severe hepatic impairment or cirrhosis
regular liver function tests and assessment for signs of hepatotoxicity
Use with caution and monitor for adverse effects.
Statistics and clinical data
Commonly prescribed since
General prescribing information
Drug class
Drug class information
Common uses
Common therapeutic uses
Mechanism of action
Pharmacological mechanism
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 22, 2026. · Read our editorial policy