Aspirin, also known as acetylsalicylic acid (ASA), is one of the oldest and most important medicines in clinical practice. It is unique among NSAIDs because it provides pain relief, fever reduction, anti-inflammatory action, and powerful antiplatelet (blood-thinning) effects. From everyday headaches to heart attack and stroke prevention, aspirin plays a life-saving role when used correctly.
This comprehensive guide explains what aspirin is, how it works, its indications, dosing, comparisons with other NSAIDs, side effects, contraindications, and common mistakes, making it ideal for students, clinicians, and general readers.
What Is Aspirin?
Aspirin (ASA) is a non-steroidal anti-inflammatory drug (NSAID) with a distinct irreversible antiplatelet effect, setting it apart from other NSAIDs.
Common brand names
- Bayer Aspirin
- Ecotrin
- Apo-ASA
Why Aspirin Is Unique Among NSAIDs
Unlike most NSAIDs, aspirin:
- Irreversibly inhibits platelets
- Has proven cardiovascular protection
- Is used in very low doses for heart disease prevention
This makes aspirin both a painkiller and a cardioprotective drug.
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Mechanism of Action
Aspirin irreversibly inhibits the enzyme Cyclooxygenase (COX-1 > COX-2).
Key Effects
1. ↓ Prostaglandins → ↓ pain, fever, inflammationExam pearl:
Platelets cannot synthesize new COX → aspirin’s antiplatelet effect lasts 7–10 days.
Clinical Uses of Aspirin
1. Pain & Fever
- Headache
- Toothache
- Musculoskeletal pain
- Fever (adults)
2. Anti-Inflammatory Uses
- Rheumatoid arthritis
- Osteoarthritis
- Acute rheumatic fever
3. Antiplatelet / Cardiovascular Uses
- Myocardial Infarction (acute & secondary prevention)
- Ischemic Stroke prevention
- Stable & unstable angina
- Post-PCI / stent patients
4. Other Important Uses
- Kawasaki disease (children, specialist-guided)
- Colorectal cancer risk reduction (long-term, selected patients)
Aspirin Dosing
| Indication | Dose |
|---|---|
| Analgesic / antipyretic | 300–600 mg every 6–8 hrs |
| Anti-inflammatory | 3–5 g/day (divided) |
| Antiplatelet (cardio) | 75–150 mg once daily |
| Acute MI | 160–325 mg (chewed) |
Aspirin vs Other NSAIDs
| Feature | Aspirin | Ibuprofen | Naproxen |
|---|---|---|---|
| Antiplatelet effect | ✅ Strong | ❌ | ❌ |
| COX inhibition | Irreversible | Reversible | Reversible |
| CV protection | ✅ | ❌ | ⚠️ |
| GI risk | High | Moderate | Moderate |
| Use in MI | Yes (gold standard) | No | No |
Benefits of Aspirin
- Proven mortality reduction in heart disease
- Low cost & widely available
- Multiple therapeutic roles
- Life-saving in acute MI
Side Effects of Aspirin
Gastrointestinal
- Gastritis
- Peptic ulcer
- GI bleeding
Bleeding Risks
- Prolonged bleeding time
- Hemorrhagic stroke (rare)
Hypersensitivity
- Aspirin-induced asthma
- Urticaria
Metabolic / Toxicity
- Reye’s Syndrome (children with viral illness)
- Salicylism: tinnitus, hyperventilation, metabolic acidosis
Contraindications
- Children with viral infections
- Active peptic ulcer disease
- Bleeding disorders
- Severe renal failure
- Aspirin-sensitive asthma
- Third trimester of pregnancy
Common Drug Interactions
- Anticoagulants → ↑ bleeding risk
- Other NSAIDs → ↑ GI toxicity
- Corticosteroids → ↑ ulcer risk
- Alcohol → ↑ GI bleeding
Common Mistakes & How to Fix Them
❌ Giving aspirin to children → Use paracetamol instead
❌ Using without GI protection → Add PPI in high-risk patients
❌ Stopping abruptly after MI → Continue lifelong unless contraindicated
❌ Confusing low-dose vs pain-dose → Dose matters
FAQs
Is aspirin a blood thinner?
It’s an antiplatelet, not a true anticoagulant.
Can aspirin prevent heart attacks?
Yes—low-dose aspirin reduces risk in selected patients.
Why is aspirin avoided in children?
Due to risk of Reye’s syndrome.
Can aspirin be taken daily?
Yes, low-dose daily aspirin is common for heart patients.
Does aspirin reduce inflammation?
Yes, at higher doses.
