Aspirin (acetylsalicylic acid)
Two very different use cases in one pill: low-dose for cardiovascular protection, and higher doses for pain and fever. The interaction profile is significant either way. Sold under brand names such as Bayer, Ecotrin, and Bufferin (acetylsalicylic acid, ASA).
What it's used for
- Low-dose (81-100mg daily): secondary prevention after heart attack or stroke; sometimes primary prevention in selected high-risk patients.
- Standard dose (325-650mg): pain, fever, inflammation.
- Acute chest pain: chewed 325mg at the onset of suspected heart attack (per emergency guidance).
How it works
Irreversibly inhibits COX-1, reducing thromboxane and making platelets less sticky for their entire lifespan (~7-10 days). This is why stopping aspirin before surgery takes about a week.
Key interactions
- Warfarin, DOACs (apixaban, rivaroxaban): major — significantly increased bleeding risk.
- Ibuprofen: moderate — can blunt the cardioprotective effect of low-dose aspirin.
- SSRIs: moderate — additive bleeding risk.
- Clopidogrel: sometimes prescribed together intentionally (dual antiplatelet therapy) but requires careful monitoring.
- Alcohol: moderate — increases GI bleeding risk.
Common side effects
GI upset, heartburn, increased bruising. Ear ringing (tinnitus) at higher doses. Serious: GI bleeding, hemorrhagic stroke. Reye's syndrome risk in children with viral illness — aspirin is generally avoided under age 16 for fever.
Who should be cautious
- History of GI ulcers or bleeding.
- Planned surgery (usually held 5-7 days before).
- Bleeding disorders or on other blood thinners.
- Pregnancy (third trimester: avoid).
What to ask your pharmacist
- Do I still need daily aspirin given current guidelines?
- Should I take an enteric-coated version?
- What should I do before a dental or surgical procedure?