Aspirin: what it does, when to use it, and what to watch for

A single low-dose aspirin can help prevent a heart attack for some people — but the same pill can cause serious bleeding for others. That makes aspirin simple to buy and tricky to use. This page gives plain, useful advice so you can make safer choices.

How aspirin works and common uses

Aspirin (acetylsalicylic acid) reduces pain, fever, and inflammation. At low doses it also reduces platelet clumping, which lowers the risk of blood clots. People take it for headaches, muscle pain, fever, and — under medical advice — to lower heart attack or stroke risk.

For sudden chest pain or suspected heart attack, chewing one 325 mg tablet while getting emergency help can be life-saving. For daily prevention, doctors usually prescribe 75–100 mg once a day when benefits outweigh bleeding risks.

Doses, safety, and who should avoid aspirin

Typical over-the-counter doses for pain range from 325 mg to 650 mg every 4–6 hours (don’t exceed label limits). Low-dose aspirin for heart protection is much smaller — 75 mg to 100 mg daily. Children and teens recovering from viral illnesses should not take aspirin because of the risk of Reye’s syndrome.

Watch for stomach pain, black stools, coughing or vomiting blood, or sudden bruising — those can be signs of bleeding. People with active ulcers, recent surgery, bleeding disorders, or a history of severe aspirin allergy should avoid it unless a doctor says otherwise.

Important drug interactions: aspirin increases bleeding risk with blood thinners (warfarin, DOACs), some antidepressants (SSRIs), and other NSAIDs (ibuprofen, naproxen). Alcohol boosts stomach bleeding risk. If you take any prescription that affects clotting, check with your clinician before starting aspirin.

Small practical tips: take aspirin with food or a glass of milk to reduce stomach upset. Enteric-coated tablets may be gentler on the stomach but don’t eliminate bleeding risk. If you need regular pain relief but also take low-dose aspirin, talk to your doctor about timing — some NSAIDs can blunt aspirin’s heart benefits.

Thinking of buying aspirin online? Choose trusted sellers, check expiry dates, and confirm the active ingredient and dose. OTC aspirin is widely available, but if you’re using it long-term for heart or stroke prevention, get a clear plan from your doctor — who will weigh benefits and bleeding risks for you personally.

Questions to ask your clinician: Do I need daily aspirin for heart protection? What dose is right for me? How do my other medicines affect aspirin? Clear answers make aspirin safer and more effective.