For most adults using aspirin for pain or fever, typical doses are 325–650 mg every 4–6 hours as needed, with an absolute maximum of about 3,900–4,000 mg (3.9–4 g) in 24 hours, but going anywhere near that upper limit can be risky without medical supervision. Because aspirin can cause serious side effects and overdose, the safest approach is to use the lowest effective dose for the shortest possible time and to confirm with a clinician or pharmacist what is right for your specific situation.

Quick Scoop

  • For short‑term pain or fever, many guidelines describe 325–650 mg every 4–6 hours, and not more than about 3,900–4,000 mg in 24 hours for adults.
  • Long‑term “baby aspirin” for heart protection is usually 75–100 mg once daily (most often 81 mg), but this should only be taken if a doctor has specifically recommended it.
  • Taking too much aspirin can cause ringing in the ears, nausea, fast breathing, confusion, and can be life‑threatening; emergency care is needed if an overdose is suspected.

Key safety checks

  • Do not give aspirin to children or teens under 19 years without medical advice because of the risk of Reye’s syndrome.
  • Avoid aspirin or get urgent medical advice if you have a history of stomach ulcers, bleeding problems, are on blood thinners, have kidney disease, are pregnant, or drink heavily.
  • Never combine multiple products that contain aspirin or other NSAIDs (like ibuprofen or naproxen) without professional guidance, since this raises bleeding and toxicity risks.

When to seek help right now

  • You took more than the package or your doctor says, or you cannot remember how many tablets you took.
  • You notice ringing in the ears, rapid breathing, severe stomach pain, vomiting, confusion, or extreme drowsiness after taking aspirin.
  • You have black or bloody stools, vomit that looks like coffee grounds, or sudden severe headache or weakness.

If you tell more about your age, other medicines, and why you want to take aspirin, a more tailored (but still non‑diagnostic) explanation can be given—however, this never replaces urgent in‑person medical care if you might have taken too much.