you arrive at the clinic and provide informed consent. the staff will ask questions about your health, perform a brief physical exam, and measure your vital signs.

you will be randomly assigned to receive either s-ibuprofen gel 5% or a placebo gel. randomization means you will not know which gel you receive, and the assignment is made by a computer.

you will receive a supply of the assigned gel, instructions on how to apply it, a pain diary to record your symptoms, and a supply of paracetamol 1000 mg tablets to use only if needed for rescue pain relief.

within a few hours after the baseline visit, apply 1.5 g of the gel to the injured area. the gel should be spread thinly over the skin and gently massaged in.

record the time of application and your pain level in the diary using the numeric rating scale (nrs), where 0 means no pain and 10 means the worst pain imaginable.

each day for the next seven days, apply 1.5 g of the same gel once every 24 hours. use the same technique as the first application.

continue to record pain scores in the diary at the scheduled times (approximately every 2–4 hours during the first day and at later time points up to 168 hours). also note any side effects or skin reactions.

if the pain becomes intolerable, you may take one tablet of paracetamol 1000 mg by mouth.

write the exact time you take the tablet and the dose in the diary. rescue medication should be used only when necessary and not exceed the amount advised by the study staff.

return to the clinic about 24 hours after the baseline visit.

the investigator will ask you to rate pain on movement (pain on movement, pom) and pain at rest (pain at rest, par) using the nrs, measure vital signs, and review your diary for completeness.

tolerability of the gel will be assessed on a simple four‑point scale, and any adverse events will be recorded.

you will attend follow‑up visits on approximately day 2, day 3, day 4, and day 7 (around 168 hours after the first application).

at each visit the same assessments as at visit 2 will be performed: nrs pain scores, vital signs, tolerability rating, and documentation of any adverse events.

the investigator will also ask about the time to first perceptible pain relief, time to meaningful relief, and any additional use of rescue medication.

the last clinic visit occurs about one week after the first gel application.

all remaining study medication will be returned, the pain diary will be collected, and a final assessment of pain, tolerability, and safety will be completed.

after this visit your participation in the trial is finished.