Aspirin

What it is

Aspirin is acetylsalicylic acid, a medicine used in low doses such as 75–100 mg to reduce blood clotting and in higher doses to relieve pain and fever. It belongs to the nonsteroidal anti-inflammatory drug (NSAID) class, but it is distinct from many other NSAIDs because it irreversibly affects platelets for their lifespan, about 7 to 10 days. Common brand names include Ecosprin and Disprin in India and elsewhere.

Aspirin has several established medical uses. At lower doses, clinicians use it to help prevent blood clots in selected people with prior heart attack, ischemic stroke, or certain forms of cardiovascular disease. At higher doses, it can reduce pain, fever, and inflammation, although many people now use other medicines such as paracetamol or ibuprofen for routine symptom relief because aspirin can irritate the stomach and increase bleeding risk.

In India, aspirin is widely available, but self-use is not always harmless. The right dose and reason matter, especially for older adults, people with ulcers, those taking blood thinners, and children with viral illnesses.

How it works

Aspirin blocks cyclooxygenase enzymes, often called COX-1 and COX-2, which lowers production of prostaglandins and thromboxane. This explains its main effects:

Effect	How aspirin causes it
Pain relief	Lowers prostaglandins involved in pain signaling
Fever reduction	Acts on temperature-regulating pathways linked to prostaglandins
Anti-inflammatory action	Reduces inflammatory prostaglandin production
Antiplatelet action	Irreversibly reduces thromboxane A2, making platelets less able to clump

The antiplatelet effect is especially important in heart and stroke care. Because platelets cannot make new COX enzyme after aspirin blocks it, the effect lasts until new platelets are produced. That is why aspirin may need to be stopped several days before some surgeries or dental procedures, but only if a clinician advises it.

Evidence and uses

Aspirin is well established for some uses and less appropriate for others.

1. Secondary prevention of cardiovascular disease: This is one of aspirin's clearest uses. In people who have already had a heart attack, ischemic stroke, transient ischemic attack, or certain artery procedures such as stent placement, aspirin can lower the risk of future clot-related events. This benefit is supported by large trials and guideline reviews.
2. Primary prevention: For people who have never had a cardiovascular event, the balance is more complicated. Some guidelines now recommend against routine aspirin use in many older adults or people at average risk because the bleeding risk may outweigh the benefit.
3. Pain, fever, and inflammation: Aspirin can treat headache, body aches, dental pain, fever, and inflammatory conditions. Still, it is not always the first choice because of stomach irritation and bleeding risk.
4. Acute heart attack care: In suspected heart attack, clinicians may advise chewing a non-enteric aspirin for faster absorption if there is no allergy or major bleeding risk. This should follow emergency medical guidance, not self-diagnosis.

A few practical comparisons are useful:

Use	Aspirin role	Common caution
Prior heart attack or stroke	Often beneficial	Bleeding risk still matters
Routine prevention in healthy adults	Often not routine anymore	Benefit may be small
Pain or fever	Works, but alternatives are common	Can upset stomach
Children with viral illness	Generally avoided	Risk of Reye's syndrome

In pregnancy, low-dose aspirin may be prescribed in selected high-risk pregnancies, such as some people at risk of preeclampsia, but this should only be done under obstetric guidance.

Safety and interactions

Aspirin can cause serious side effects, especially bleeding. The most common problems are stomach upset, heartburn, nausea, and easy bruising. More serious risks include stomach ulcers, gastrointestinal bleeding, bleeding in the brain, and allergic reactions including aspirin-exacerbated respiratory disease in some people with asthma or nasal polyps.

Children and teenagers with suspected viral infections should generally not take aspirin because of the risk of Reye's syndrome, a rare but serious condition affecting the liver and brain.

Important interactions include:

Medicine or substance	Why it matters
Warfarin, apixaban, rivaroxaban, heparin	Higher bleeding risk
Clopidogrel and other antiplatelet drugs	Additive bleeding risk
Ibuprofen and some other NSAIDs	More stomach bleeding; ibuprofen may interfere with aspirin's antiplatelet effect if timed poorly
Steroids	Higher ulcer and bleeding risk
SSRIs such as sertraline or fluoxetine	Higher gastrointestinal bleeding risk
Alcohol	Can increase stomach irritation and bleeding
Methotrexate	Aspirin can raise methotrexate toxicity risk in some settings

People with a history of peptic ulcer disease, bleeding disorders, kidney disease, severe liver disease, uncontrolled high blood pressure, or aspirin allergy should be especially cautious. Enteric-coated aspirin may reduce stomach irritation for some people, but it does not remove the risk of internal bleeding.

Do not start daily aspirin on your own for heart protection. Talk to a clinician or pharmacist about whether the expected benefit is greater than the bleeding risk.

When to see a clinician

Seek urgent care right away for black stools, vomiting blood, severe stomach pain, sudden weakness, trouble speaking, chest pain, severe shortness of breath, or signs of an allergic reaction such as wheezing or facial swelling.

Contact a clinician before using aspirin regularly if you are over 60, have had ulcers or bleeding, take blood thinners, have asthma, are pregnant, or are planning surgery. If you are taking aspirin after a heart attack, stroke, or stent, do not stop it without medical advice because stopping suddenly can increase clotting risk in some situations.

In India, aspirin is easy to buy, but long-term use should still be reviewed by a qualified clinician, especially when multiple medicines are involved.

Limitations and open questions

Aspirin is a proven medicine, but it is not right for everyone. The biggest limitation is the tradeoff between benefit and bleeding, especially in primary prevention. Recent guideline changes reflect this more cautious approach.

Evidence is also mixed on whether aspirin helps prevent some cancers in the general population. Some studies have suggested possible colorectal cancer benefit with long-term use, but this is not a reason to self-prescribe because bleeding risk is immediate and individual risk varies.

Another practical limitation is that people often assume low-dose aspirin is harmless because it is common and inexpensive. It is not. The best use of aspirin depends on the reason for taking it, the dose, age, ulcer history, other medicines, and overall cardiovascular risk.