Ibuprofen typically begins to work within 20 to 30 minutes after ingestion, with its maximum effects reached in about 1 to 2 hours. The pain relief effects of a single dose generally last between 4 to 6 hours, though some sources mention effects lasting up to 6 to 8 hours depending on the dose and individual factors such as age, weight, metabolism, and health conditions

. Regarding how long ibuprofen stays in the body, it has a relatively short half-life of about 1.8 to 2.2 hours, meaning that it takes roughly 10 hours (4 to 5 half-lives) for the drug to be mostly eliminated from the system. After this time, about 97% of the drug is cleared from the body. The liver metabolizes ibuprofen into inactive substances, which are then excreted in urine

. In summary:

• Onset of action: 20–30 minutes
• Peak effect: 1–2 hours
• Duration of pain relief: 4–6 hours (sometimes up to 6–8 hours)
• Time to clear from system: approximately 10 hours

Factors such as food intake, dosage, and individual metabolism can influence these timings. Taking ibuprofen on an empty stomach may speed relief but increase stomach side effects. Higher doses or long-acting forms may extend the duration of effect