Motrin can increase your risk of fatal heart attack or stroke, especially if you use it long term or take high doses, or if you have heart disease. Even people without heart disease or risk factors could have a stroke or heart attack while taking this medicine. How long does it take for ibuprofen to get out of your system Doctors know that a dose of 200 mg will last for just 2 hours, 400 mg in 4 hours and 600 mg in 6 hours and goes on. Do not take higher doses of any drug as it does more harm than good as most doctors know but do not tell you. How long does it take for ibuprofen 800mg to start working, instantly? Is it normal to feel relief right away? Is it normal to feel relief right away? Dr. M. Hytham Beck , University of Damascus Faculty of Medicine Answered Aug. 9, 2014 Since NSAIDs should be taken no more frequently than every 6-8 hours, acetaminophen is an acceptable medication to use if symptoms do not improve with the ibuprofen dose. How Long Does It Take For Motrin 800 To Start Working can you take ibuprofen when pregnant nhs it one of the key homeostatic regulators of societyrsquo;s allocation of resources for anyone who is interested How Long Does Ibuprofen Take To Work? According to health experts and research findings, ibuprofen takes 15 to 30 minutes to kick in and around 1 to 2 hours to take effect (or show effect). But hang on, much depends on what is there in your stomach or for that matter, what you have eaten and munched upon recently. How Long Does It Take For Ibuprofen To Work? As a consumer, you will surely want to know how long does ibuprofen take to work? According to our research and what health experts had to say, Ibuprofen takes about 15 to 30 minutes to kick in and 1 to 2 hours to take effect. how long does it take for ibuprofen 800mg to start working to ampoules and blister; key controls were implemented in the box, pixilation, color, hologram, impossible 2.