how long does it take ibuprofen to start working
Report Abuse. Ibuprofen (motrin) will take aproximatly 15-20 minutes to take effect. It is also very unsafe to take more than 800 mg every 12 hrs. Mortin is very rough on the GI tract and specifically the stomach.Take it with food or milk. If the mortin isnt working it may be time to see a doctor.