For the general population, what I was taught as a pharmacist is that Acetaminophen = Tylenol is fine as long as one is aware that Acetaminophen is found in many combination products such as Percocet and Vicodin and over the counter cold medications. Since overdoses do not take long to affect the liver, it was thought to lower the maximum daily dose of acetaminophen from 4000 mg/24 hrs to 3000mg/24 hrs. It does not work on inflammation.
Ibuprofen is considered among the safest NSAID rarely causing severe acute liver injury in low doses. However per another nih article, higher rates of ALT elevations occur with high full doses of 2400-3200mg a day. These elevations were noted to be mild rarely above 100 iu/L. There are very rare cases of acute cholesterol liver injury.
If there is already liver damage, it is best to check with your hepatologist.
I found an interesting article on Pain management in cirrhotic patients, it RECOMMENDS ACETAMINOPHEN AT REDUCED DOSES. For patients with cirrhosis, it says NSAIDs should be avoided to avert renal failure and opiates should be used sparingly to prevent encephalopathy.
This is probably too much info. But I hope this helps. I don’t know what f3 fibrosis is but if you don’t have cirrhosis and have severe pain that low doses of either drug is not adequate, it may be ok to alternate between the 2 meds if needed as they often do this for kids with fever so the meds can be given at shorter intervals.